diff --git a/AGENTS.md b/AGENTS.md
index 54ddd51..5d50f89 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -17,7 +17,6 @@
 - Every new public API member must have XML documentation matching the quality of the surrounding API.
 - New protected members that define engine contracts or are intended for derived engine implementations must also have XML documentation.
 - The documentation requirements do not apply to the `EPPlus45-FixCalcsEdition.MultiTarget` project or to `TestAndDemoExcelOps`; do not make documentation-only changes there.
-- The HTML export API classes are currently excluded from documentation cleanup because they are tracked for a separate follow-up ticket.
 - Historical documentation baselines should stay at zero. If a member is intentionally out of scope, add a narrow checker exclusion instead of raising a global allowance.
 - Public enums and their values must be documented.
 - Keep `<summary>` text short and focused, for example `Insert one or more columns.`.
@@ -43,6 +42,14 @@
 - Static test workbooks belong in the appropriate `test_data` directories.
 - When repository copy/clone scripts generate or synchronize shared source or test files, include the resulting copied files in the same change.
 
+## Release Process
+
+- Create releases only from the repository's primary integration branch, currently `main` or `master`.
+- Do not create a release from a feature branch, ticket branch, Codex branch, or any other branch that has not been merged into the primary integration branch.
+- Before creating a release, ensure the pull request has been created, reviewed as required, merged into the primary integration branch, and the build-and-test workflow for that branch has completed successfully.
+- If the workflow is configured to run on pull requests and on pushes to the primary integration branch, wait for the relevant successful run after merge before creating the release.
+- If a release is requested before these prerequisites are met, create or update the pull request first and explicitly tell the user that the release must wait for the successful build-and-test pipeline on the primary integration branch.
+
 ## File Encoding and Line Endings
 
 - Save text files as UTF-8 with BOM and CRLF line endings, matching `.editorconfig`.
diff --git a/ExcelOps-EpplusFreeFixCalcsEdition/EpplusFreeExcelDataOperations.SharedCode.vb b/ExcelOps-EpplusFreeFixCalcsEdition/EpplusFreeExcelDataOperations.SharedCode.vb
index dc3bc12..ddf71ad 100644
--- a/ExcelOps-EpplusFreeFixCalcsEdition/EpplusFreeExcelDataOperations.SharedCode.vb
+++ b/ExcelOps-EpplusFreeFixCalcsEdition/EpplusFreeExcelDataOperations.SharedCode.vb
@@ -407,15 +407,34 @@ Namespace ExcelOps
 
         ''' <inheritdoc/>
         Protected Overrides Sub LoadWorkbook(file As System.IO.FileInfo)
-            If Me.PasswordForOpening <> Nothing Then
-                Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(file, Me.PasswordForOpening)
-            Else
-                Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(file)
+            If IsUnsupportedBinaryXlsFile(file) Then
+                Throw New BinaryXlsFileNotSupportedException(file)
             End If
-            Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
+            If IsUnsupportedBinaryXlsbFile(file) Then
+                Throw New BinaryXlsbFileNotSupportedException(file)
+            End If
+            Try
+                If Me.PasswordForOpening <> Nothing Then
+                    Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(file, Me.PasswordForOpening)
+                Else
+                    Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(file)
+                End If
+            Catch ex As Exception When IsUnsupportedBinaryXlsFile(file)
+                Throw New BinaryXlsFileNotSupportedException(file, ex)
+            Catch ex As Exception When IsPasswordProtectedFilePasswordMismatch(file)
+                Throw New FilePasswordProtectedMismatchException(file, ex)
+            End Try
+            If String.Equals(file.Extension, ".xlsb", StringComparison.OrdinalIgnoreCase) Then
+                Throw New BinaryXlsbFileNotSupportedException(file)
+            End If
+            Try
+                Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
 
-            'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
-            Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+                'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
+                Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+            Catch ex As System.Xml.XmlException
+                Throw New FileCorruptedOrInvalidFileFormatException(file, ex)
+            End Try
         End Sub
 
         ''' <inheritdoc/>
@@ -428,17 +447,131 @@ Namespace ExcelOps
 
         ''' <inheritdoc/>
         Protected Overrides Sub LoadWorkbook(data As System.IO.Stream)
-            If Me.PasswordForOpening <> Nothing Then
-                Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(data, Me.PasswordForOpening)
-            Else
-                Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(data)
+            If IsUnsupportedBinaryXlsData(data) Then
+                Throw New BinaryXlsFileNotSupportedException(CType(Nothing, String))
             End If
-            Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
+            If IsUnsupportedBinaryXlsbData(data) Then
+                Throw New BinaryXlsbFileNotSupportedException(CType(Nothing, String))
+            End If
+            Try
+                If Me.PasswordForOpening <> Nothing Then
+                    Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(data, Me.PasswordForOpening)
+                Else
+                    Me._WorkbookPackage = New CompuMaster.Epplus4.ExcelPackage(data)
+                End If
+            Catch ex As Exception When IsUnsupportedBinaryXlsData(data)
+                Throw New BinaryXlsFileNotSupportedException(CType(Nothing, String), ex)
+            Catch ex As Exception When IsPasswordProtectedDataPasswordMismatch(data)
+                Throw New FilePasswordProtectedMismatchException(CType(Nothing, String), ex)
+            End Try
+            Try
+                Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
 
-            'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
-            Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+                'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
+                Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+            Catch ex As System.Xml.XmlException
+                Throw New FileCorruptedOrInvalidFileFormatException(CType(Nothing, String), ex)
+            End Try
         End Sub
 
+        Private Shared Function IsUnsupportedBinaryXlsFile(file As FileInfo) As Boolean
+            Using stream As FileStream = file.OpenRead()
+                Return IsUnsupportedBinaryXlsData(stream)
+            End Using
+        End Function
+
+        Private Shared Function IsUnsupportedBinaryXlsbFile(file As FileInfo) As Boolean
+            Using stream As FileStream = file.OpenRead()
+                Return IsUnsupportedBinaryXlsbData(stream)
+            End Using
+        End Function
+
+        Private Shared Function IsPasswordProtectedFilePasswordMismatch(file As FileInfo) As Boolean
+            Using stream As FileStream = file.OpenRead()
+                Return IsPasswordProtectedDataPasswordMismatch(stream)
+            End Using
+        End Function
+
+        Private Shared Function IsUnsupportedBinaryXlsData(stream As Stream) As Boolean
+            Return IsOleCompoundDocument(stream) AndAlso Not ContainsOleDirectoryName(stream, "EncryptedPackage")
+        End Function
+
+        Private Shared Function IsUnsupportedBinaryXlsbData(stream As Stream) As Boolean
+            Return ContainsZipEntryName(stream, "xl/workbook.bin")
+        End Function
+
+        Private Shared Function IsPasswordProtectedDataPasswordMismatch(stream As Stream) As Boolean
+            Return IsOleCompoundDocument(stream) AndAlso ContainsOleDirectoryName(stream, "EncryptedPackage")
+        End Function
+
+        Private Shared Function IsOleCompoundDocument(stream As Stream) As Boolean
+            Dim header = ReadHeader(stream, 8)
+            Dim oleHeader As Byte() = {&HD0, &HCF, &H11, &HE0, &HA1, &HB1, &H1A, &HE1}
+            Return ContainsBytes(header, oleHeader)
+        End Function
+
+        Private Shared Function ContainsOleDirectoryName(stream As Stream, name As String) As Boolean
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Using copy As New MemoryStream()
+                    stream.CopyTo(copy)
+                    Dim data As Byte() = copy.ToArray()
+                    Dim asciiNeedle As Byte() = Encoding.ASCII.GetBytes(name)
+                    Dim unicodeNeedle As Byte() = Encoding.Unicode.GetBytes(name)
+                    Return ContainsBytes(data, asciiNeedle) OrElse ContainsBytes(data, unicodeNeedle)
+                End Using
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ContainsZipEntryName(stream As Stream, name As String) As Boolean
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Using copy As New MemoryStream()
+                    stream.CopyTo(copy)
+                    Dim data As Byte() = copy.ToArray()
+                    Dim asciiNeedle As Byte() = Encoding.ASCII.GetBytes(name)
+                    Return ContainsBytes(data, asciiNeedle)
+                End Using
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ReadHeader(stream As Stream, count As Integer) As Byte()
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Dim buffer(count - 1) As Byte
+                Dim read As Integer = stream.Read(buffer, 0, buffer.Length)
+                If read <> buffer.Length Then Array.Resize(buffer, read)
+                Return buffer
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ContainsBytes(data As Byte(), pattern As Byte()) As Boolean
+            If pattern.Length = 0 OrElse data.Length < pattern.Length Then Return False
+            For index As Integer = 0 To data.Length - pattern.Length
+                Dim found As Boolean = True
+                For patternIndex As Integer = 0 To pattern.Length - 1
+                    If data(index + patternIndex) <> pattern(patternIndex) Then
+                        found = False
+                        Exit For
+                    End If
+                Next
+                If found Then Return True
+            Next
+            Return False
+        End Function
+
         ''' <inheritdoc/>
         Public Overrides Function LookupLastCell(sheetName As String) As ExcelOps.ExcelCell
             If sheetName = Nothing Then Throw New ArgumentNullException(NameOf(sheetName))
diff --git a/ExcelOps-EpplusPolyform/EpplusPolyformExcelDataOperations.SharedCode.vb b/ExcelOps-EpplusPolyform/EpplusPolyformExcelDataOperations.SharedCode.vb
index d0291c1..e1bb097 100644
--- a/ExcelOps-EpplusPolyform/EpplusPolyformExcelDataOperations.SharedCode.vb
+++ b/ExcelOps-EpplusPolyform/EpplusPolyformExcelDataOperations.SharedCode.vb
@@ -407,15 +407,34 @@ Namespace ExcelOps
 
         ''' <inheritdoc/>
         Protected Overrides Sub LoadWorkbook(file As System.IO.FileInfo)
-            If Me.PasswordForOpening <> Nothing Then
-                Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(file, Me.PasswordForOpening)
-            Else
-                Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(file)
+            If IsUnsupportedBinaryXlsFile(file) Then
+                Throw New BinaryXlsFileNotSupportedException(file)
             End If
-            Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
+            If IsUnsupportedBinaryXlsbFile(file) Then
+                Throw New BinaryXlsbFileNotSupportedException(file)
+            End If
+            Try
+                If Me.PasswordForOpening <> Nothing Then
+                    Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(file, Me.PasswordForOpening)
+                Else
+                    Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(file)
+                End If
+            Catch ex As Exception When IsUnsupportedBinaryXlsFile(file)
+                Throw New BinaryXlsFileNotSupportedException(file, ex)
+            Catch ex As Exception When IsPasswordProtectedFilePasswordMismatch(file)
+                Throw New FilePasswordProtectedMismatchException(file, ex)
+            End Try
+            If String.Equals(file.Extension, ".xlsb", StringComparison.OrdinalIgnoreCase) Then
+                Throw New BinaryXlsbFileNotSupportedException(file)
+            End If
+            Try
+                Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
 
-            'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
-            Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+                'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
+                Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+            Catch ex As System.Xml.XmlException
+                Throw New FileCorruptedOrInvalidFileFormatException(file, ex)
+            End Try
         End Sub
 
         ''' <inheritdoc/>
@@ -428,17 +447,131 @@ Namespace ExcelOps
 
         ''' <inheritdoc/>
         Protected Overrides Sub LoadWorkbook(data As System.IO.Stream)
-            If Me.PasswordForOpening <> Nothing Then
-                Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(data, Me.PasswordForOpening)
-            Else
-                Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(data)
+            If IsUnsupportedBinaryXlsData(data) Then
+                Throw New BinaryXlsFileNotSupportedException(CType(Nothing, String))
             End If
-            Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
+            If IsUnsupportedBinaryXlsbData(data) Then
+                Throw New BinaryXlsbFileNotSupportedException(CType(Nothing, String))
+            End If
+            Try
+                If Me.PasswordForOpening <> Nothing Then
+                    Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(data, Me.PasswordForOpening)
+                Else
+                    Me._WorkbookPackage = New OfficeOpenXml.ExcelPackage(data)
+                End If
+            Catch ex As Exception When IsUnsupportedBinaryXlsData(data)
+                Throw New BinaryXlsFileNotSupportedException(CType(Nothing, String), ex)
+            Catch ex As Exception When IsPasswordProtectedDataPasswordMismatch(data)
+                Throw New FilePasswordProtectedMismatchException(CType(Nothing, String), ex)
+            End Try
+            Try
+                Me._WorkbookPackage.Compatibility.IsWorksheets1Based = False
 
-            'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
-            Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+                'set workbook FullCalcOnLoad always to False since it's already triggered using property of Me.AutoCalculationOnLoad
+                Me.Workbook.FullCalcOnLoad = Me.AutoCalculationOnLoad 'unknown if executed after loading already completed or if it's a workbook setting with effect on opening as user in MS Excel, too
+            Catch ex As System.Xml.XmlException
+                Throw New FileCorruptedOrInvalidFileFormatException(CType(Nothing, String), ex)
+            End Try
         End Sub
 
+        Private Shared Function IsUnsupportedBinaryXlsFile(file As FileInfo) As Boolean
+            Using stream As FileStream = file.OpenRead()
+                Return IsUnsupportedBinaryXlsData(stream)
+            End Using
+        End Function
+
+        Private Shared Function IsUnsupportedBinaryXlsbFile(file As FileInfo) As Boolean
+            Using stream As FileStream = file.OpenRead()
+                Return IsUnsupportedBinaryXlsbData(stream)
+            End Using
+        End Function
+
+        Private Shared Function IsPasswordProtectedFilePasswordMismatch(file As FileInfo) As Boolean
+            Using stream As FileStream = file.OpenRead()
+                Return IsPasswordProtectedDataPasswordMismatch(stream)
+            End Using
+        End Function
+
+        Private Shared Function IsUnsupportedBinaryXlsData(stream As Stream) As Boolean
+            Return IsOleCompoundDocument(stream) AndAlso Not ContainsOleDirectoryName(stream, "EncryptedPackage")
+        End Function
+
+        Private Shared Function IsUnsupportedBinaryXlsbData(stream As Stream) As Boolean
+            Return ContainsZipEntryName(stream, "xl/workbook.bin")
+        End Function
+
+        Private Shared Function IsPasswordProtectedDataPasswordMismatch(stream As Stream) As Boolean
+            Return IsOleCompoundDocument(stream) AndAlso ContainsOleDirectoryName(stream, "EncryptedPackage")
+        End Function
+
+        Private Shared Function IsOleCompoundDocument(stream As Stream) As Boolean
+            Dim header = ReadHeader(stream, 8)
+            Dim oleHeader As Byte() = {&HD0, &HCF, &H11, &HE0, &HA1, &HB1, &H1A, &HE1}
+            Return ContainsBytes(header, oleHeader)
+        End Function
+
+        Private Shared Function ContainsOleDirectoryName(stream As Stream, name As String) As Boolean
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Using copy As New MemoryStream()
+                    stream.CopyTo(copy)
+                    Dim data As Byte() = copy.ToArray()
+                    Dim asciiNeedle As Byte() = Encoding.ASCII.GetBytes(name)
+                    Dim unicodeNeedle As Byte() = Encoding.Unicode.GetBytes(name)
+                    Return ContainsBytes(data, asciiNeedle) OrElse ContainsBytes(data, unicodeNeedle)
+                End Using
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ContainsZipEntryName(stream As Stream, name As String) As Boolean
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Using copy As New MemoryStream()
+                    stream.CopyTo(copy)
+                    Dim data As Byte() = copy.ToArray()
+                    Dim asciiNeedle As Byte() = Encoding.ASCII.GetBytes(name)
+                    Return ContainsBytes(data, asciiNeedle)
+                End Using
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ReadHeader(stream As Stream, count As Integer) As Byte()
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Dim buffer(count - 1) As Byte
+                Dim read As Integer = stream.Read(buffer, 0, buffer.Length)
+                If read <> buffer.Length Then Array.Resize(buffer, read)
+                Return buffer
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ContainsBytes(data As Byte(), pattern As Byte()) As Boolean
+            If pattern.Length = 0 OrElse data.Length < pattern.Length Then Return False
+            For index As Integer = 0 To data.Length - pattern.Length
+                Dim found As Boolean = True
+                For patternIndex As Integer = 0 To pattern.Length - 1
+                    If data(index + patternIndex) <> pattern(patternIndex) Then
+                        found = False
+                        Exit For
+                    End If
+                Next
+                If found Then Return True
+            Next
+            Return False
+        End Function
+
         ''' <inheritdoc/>
         Public Overrides Function LookupLastCell(sheetName As String) As ExcelOps.ExcelCell
             If sheetName = Nothing Then Throw New ArgumentNullException(NameOf(sheetName))
diff --git a/ExcelOps-FreeSpireXls/FreeSpireXlsDataOperations.SharedCode.vb b/ExcelOps-FreeSpireXls/FreeSpireXlsDataOperations.SharedCode.vb
index 3812bde..a6a10db 100644
--- a/ExcelOps-FreeSpireXls/FreeSpireXlsDataOperations.SharedCode.vb
+++ b/ExcelOps-FreeSpireXls/FreeSpireXlsDataOperations.SharedCode.vb
@@ -339,7 +339,11 @@ Namespace ExcelOps
         Protected Overrides Sub LoadWorkbook(file As System.IO.FileInfo)
             Me._Workbook = New Spire.Xls.Workbook
             Me.Workbook.OpenPassword = Me.PasswordForOpening
-            Me.Workbook.LoadFromFile(file.FullName)
+            Try
+                Me.Workbook.LoadFromFile(file.FullName)
+            Catch ex As Exception When IsPasswordProtectedFilePasswordMismatch(ex)
+                Throw New FilePasswordProtectedMismatchException(file, ex)
+            End Try
         End Sub
 
         ''' <inheritdoc/>
@@ -354,9 +358,19 @@ Namespace ExcelOps
         Protected Overrides Sub LoadWorkbook(data As IO.Stream)
             Me._Workbook = New Spire.Xls.Workbook
             Me.Workbook.OpenPassword = Me.PasswordForOpening
-            Me.Workbook.LoadFromStream(data)
+            Try
+                Me.Workbook.LoadFromStream(data)
+            Catch ex As Exception When IsPasswordProtectedFilePasswordMismatch(ex)
+                Throw New FilePasswordProtectedMismatchException(CType(Nothing, String), ex)
+            End Try
         End Sub
 
+        Private Shared Function IsPasswordProtectedFilePasswordMismatch(ex As Exception) As Boolean
+            Return ex IsNot Nothing AndAlso ex.Message IsNot Nothing AndAlso
+                (ex.Message.IndexOf("Invalid password", StringComparison.OrdinalIgnoreCase) >= 0 OrElse
+                 ex.Message.IndexOf("provide password", StringComparison.OrdinalIgnoreCase) >= 0)
+        End Function
+
         ''' <inheritdoc/>
         Public Overrides Function LookupLastCell(sheetName As String) As ExcelOps.ExcelCell
             If sheetName = Nothing Then Throw New ArgumentNullException(NameOf(sheetName))
diff --git a/ExcelOps-MicrosoftExcel/ExcelOpsLowLevel/MsExcelDataOperations.vb b/ExcelOps-MicrosoftExcel/ExcelOpsLowLevel/MsExcelDataOperations.vb
index ddd85a3..b9d1c43 100644
--- a/ExcelOps-MicrosoftExcel/ExcelOpsLowLevel/MsExcelDataOperations.vb
+++ b/ExcelOps-MicrosoftExcel/ExcelOpsLowLevel/MsExcelDataOperations.vb
@@ -466,7 +466,11 @@ Namespace Global.CompuMaster.Excel.ExcelOps
                     End If
                 Catch ex As System.Runtime.InteropServices.COMException
                     If ex.ErrorCode = &H800A03EC Then
-                        Throw New FileCorruptedOrInvalidFileFormatException(file, ex)
+                        If IsPasswordProtectedFilePasswordMismatch(file) OrElse IsPasswordProtectedFilePasswordMismatch(ex) Then
+                            Throw New FilePasswordProtectedMismatchException(file, ex)
+                        Else
+                            Throw New FileCorruptedOrInvalidFileFormatException(file, ex)
+                        End If
                     Else
                         Throw
                     End If
@@ -490,6 +494,69 @@ Namespace Global.CompuMaster.Excel.ExcelOps
             Throw New NotSupportedException()
         End Sub
 
+        Private Shared Function IsPasswordProtectedFilePasswordMismatch(file As System.IO.FileInfo) As Boolean
+            Using stream As System.IO.FileStream = file.OpenRead()
+                Return IsOleCompoundDocument(stream) AndAlso ContainsOleDirectoryName(stream, "EncryptedPackage")
+            End Using
+        End Function
+
+        Private Shared Function IsPasswordProtectedFilePasswordMismatch(ex As Exception) As Boolean
+            If ex Is Nothing OrElse ex.Message Is Nothing Then Return False
+            Return ex.Message.IndexOf("password", StringComparison.OrdinalIgnoreCase) >= 0 OrElse ex.Message.IndexOf("Kennwort", StringComparison.OrdinalIgnoreCase) >= 0
+        End Function
+
+        Private Shared Function IsOleCompoundDocument(stream As System.IO.Stream) As Boolean
+            Dim header = ReadHeader(stream, 8)
+            Dim oleHeader As Byte() = {&HD0, &HCF, &H11, &HE0, &HA1, &HB1, &H1A, &HE1}
+            Return ContainsBytes(header, oleHeader)
+        End Function
+
+        Private Shared Function ContainsOleDirectoryName(stream As System.IO.Stream, name As String) As Boolean
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Using copy As New System.IO.MemoryStream()
+                    stream.CopyTo(copy)
+                    Dim data As Byte() = copy.ToArray()
+                    Dim asciiNeedle As Byte() = Encoding.ASCII.GetBytes(name)
+                    Dim unicodeNeedle As Byte() = Encoding.Unicode.GetBytes(name)
+                    Return ContainsBytes(data, asciiNeedle) OrElse ContainsBytes(data, unicodeNeedle)
+                End Using
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ReadHeader(stream As System.IO.Stream, count As Integer) As Byte()
+            Dim originalPosition As Long? = Nothing
+            If stream.CanSeek Then originalPosition = stream.Position
+            Try
+                If stream.CanSeek Then stream.Position = 0
+                Dim buffer(count - 1) As Byte
+                Dim read As Integer = stream.Read(buffer, 0, buffer.Length)
+                If read <> buffer.Length Then Array.Resize(buffer, read)
+                Return buffer
+            Finally
+                If originalPosition.HasValue Then stream.Position = originalPosition.Value
+            End Try
+        End Function
+
+        Private Shared Function ContainsBytes(data As Byte(), pattern As Byte()) As Boolean
+            If pattern.Length = 0 OrElse data.Length < pattern.Length Then Return False
+            For index As Integer = 0 To data.Length - pattern.Length
+                Dim found As Boolean = True
+                For patternIndex As Integer = 0 To pattern.Length - 1
+                    If data(index + patternIndex) <> pattern(patternIndex) Then
+                        found = False
+                        Exit For
+                    End If
+                Next
+                If found Then Return True
+            Next
+            Return False
+        End Function
+
         ''' <inheritdoc/>
         Public Overrides Sub CleanupRangeNames()
             'do nothing - just needs to be done once, see Epplus implementation
diff --git a/ExcelOps-SpireXls/SpireXlsDataOperations.SharedCode.vb b/ExcelOps-SpireXls/SpireXlsDataOperations.SharedCode.vb
index 17cbb2f..dc28806 100644
--- a/ExcelOps-SpireXls/SpireXlsDataOperations.SharedCode.vb
+++ b/ExcelOps-SpireXls/SpireXlsDataOperations.SharedCode.vb
@@ -339,7 +339,11 @@ Namespace ExcelOps
         Protected Overrides Sub LoadWorkbook(file As System.IO.FileInfo)
             Me._Workbook = New Spire.Xls.Workbook
             Me.Workbook.OpenPassword = Me.PasswordForOpening
-            Me.Workbook.LoadFromFile(file.FullName)
+            Try
+                Me.Workbook.LoadFromFile(file.FullName)
+            Catch ex As Exception When IsPasswordProtectedFilePasswordMismatch(ex)
+                Throw New FilePasswordProtectedMismatchException(file, ex)
+            End Try
         End Sub
 
         ''' <inheritdoc/>
@@ -354,9 +358,19 @@ Namespace ExcelOps
         Protected Overrides Sub LoadWorkbook(data As IO.Stream)
             Me._Workbook = New Spire.Xls.Workbook
             Me.Workbook.OpenPassword = Me.PasswordForOpening
-            Me.Workbook.LoadFromStream(data)
+            Try
+                Me.Workbook.LoadFromStream(data)
+            Catch ex As Exception When IsPasswordProtectedFilePasswordMismatch(ex)
+                Throw New FilePasswordProtectedMismatchException(CType(Nothing, String), ex)
+            End Try
         End Sub
 
+        Private Shared Function IsPasswordProtectedFilePasswordMismatch(ex As Exception) As Boolean
+            Return ex IsNot Nothing AndAlso ex.Message IsNot Nothing AndAlso
+                (ex.Message.IndexOf("Invalid password", StringComparison.OrdinalIgnoreCase) >= 0 OrElse
+                 ex.Message.IndexOf("provide password", StringComparison.OrdinalIgnoreCase) >= 0)
+        End Function
+
         ''' <inheritdoc/>
         Public Overrides Function LookupLastCell(sheetName As String) As ExcelOps.ExcelCell
             If sheetName = Nothing Then Throw New ArgumentNullException(NameOf(sheetName))
diff --git a/ExcelOps/ExcelOpsLowLevel/ExcelDataOperationsBase.vb b/ExcelOps/ExcelOpsLowLevel/ExcelDataOperationsBase.vb
index 9833f2e..32ce71b 100644
--- a/ExcelOps/ExcelOpsLowLevel/ExcelDataOperationsBase.vb
+++ b/ExcelOps/ExcelOpsLowLevel/ExcelDataOperationsBase.vb
@@ -2320,6 +2320,9 @@ Namespace ExcelOps
             End Select
         End Sub
 
+        ''' <summary>
+        ''' Defines which parts of an HTML document are emitted for worksheet export.
+        ''' </summary>
         Public Enum HtmlDocumentExportParts As Byte
             ''' <summary>
             ''' Creates a full HTML document with header tags, style tags, etc.
diff --git a/ExcelOps/ExcelOpsLowLevel/HtmlSheetExportOptions.vb b/ExcelOps/ExcelOpsLowLevel/HtmlSheetExportOptions.vb
index ec01f7a..ce07aac 100644
--- a/ExcelOps/ExcelOpsLowLevel/HtmlSheetExportOptions.vb
+++ b/ExcelOps/ExcelOpsLowLevel/HtmlSheetExportOptions.vb
@@ -4,98 +4,136 @@ Imports System.Text
 
 Namespace ExcelOps
 
+    ''' <summary>
+    ''' Defines options for exporting a worksheet to HTML.
+    ''' </summary>
     Public Class HtmlSheetExportOptions
 
+        ''' <summary>
+        ''' Creates a new HTML worksheet export options instance.
+        ''' </summary>
         Public Sub New()
         End Sub
 
+        ''' <summary>
+        ''' Defines how a worksheet title is rendered before exported worksheet data.
+        ''' </summary>
         Public Enum SheetTitleStyles As Integer
+            ''' <summary>
+            ''' Does not render a worksheet title.
+            ''' </summary>
             None = 0
+            ''' <summary>
+            ''' Renders the worksheet title as an H1 element.
+            ''' </summary>
             H1 = 1
+            ''' <summary>
+            ''' Renders the worksheet title as an H2 element.
+            ''' </summary>
             H2 = 2
+            ''' <summary>
+            ''' Renders the worksheet title as an H3 element.
+            ''' </summary>
             H3 = 3
+            ''' <summary>
+            ''' Renders the worksheet title as an H4 element.
+            ''' </summary>
             H4 = 4
+            ''' <summary>
+            ''' Renders the worksheet title as an H5 element.
+            ''' </summary>
             H5 = 5
+            ''' <summary>
+            ''' Renders the worksheet title as an H6 element.
+            ''' </summary>
             H6 = 6
+            ''' <summary>
+            ''' Renders the worksheet title as a paragraph element.
+            ''' </summary>
             P = 10
         End Enum
 
         ''' <summary>
-        ''' Add a header before the sheet data
+        ''' Gets or sets how the worksheet name is rendered before worksheet data.
         ''' </summary>
-        ''' <returns></returns>
         Public Property ExportSheetNameAsTitle As SheetTitleStyles
 
         ''' <summary>
-        ''' Cells of these row indexes will be converted to TH cells instead of TD cells
+        ''' Gets or sets row indexes whose cells are rendered as TH elements instead of TD elements.
         ''' </summary>
-        ''' <returns></returns>
         Public Property ConsiderRowIndexesAsTableHeader As List(Of Integer)
 
         ''' <summary>
-        ''' The class name for the table in HTML
+        ''' Gets or sets the CSS class name used for generated worksheet tables.
         ''' </summary>
-        ''' <returns></returns>
         Public Property TableCssClassName As String = "xlTable"
 
 #Disable Warning CA1805 ' Keine unnötige Initialisierung
+        ''' <summary>
+        ''' Gets or sets the zero-based index of the first worksheet row to export.
+        ''' </summary>
         Public Property FirstRowIndex As Integer = 0
+        ''' <summary>
+        ''' Gets or sets the zero-based index of the first worksheet column to export.
+        ''' </summary>
         Public Property FirstColumnIndex As Integer = 0
+        ''' <summary>
+        ''' Gets or sets the zero-based index of the last worksheet row to export.
+        ''' </summary>
         Public Property LastRowIndex As Integer?
+        ''' <summary>
+        ''' Gets or sets the zero-based index of the last worksheet column to export.
+        ''' </summary>
         Public Property LastColumnIndex As Integer?
 #Enable Warning CA1805 ' Keine unnötige Initialisierung
 
+        ''' <summary>
+        ''' Gets or sets the HTML emitted when a worksheet has no exportable content.
+        ''' </summary>
         Public Property HtmlForEmptySheet As String
 
         ''' <summary>
-        ''' HTML code on top of everything (including html and head tags)
+        ''' Gets or sets the HTML emitted before generated worksheet content, including HTML and HEAD tags.
         ''' </summary>
-        ''' <returns></returns>
         Public Property HtmlDocumentHeader As String
 
         ''' <summary>
-        ''' HTML code on top of exported sheets (usually &lt;/head&gt;&lt;body&gt;)
+        ''' Gets or sets the HTML emitted between the document header and exported worksheets.
         ''' </summary>
-        ''' <returns></returns>
         Public Property HtmlDocumentHeaderEndAndBeginOfBody As String
 
         ''' <summary>
-        ''' HTML code on bottom of everything (usually &lt;/body&gt;&lt;/html&gt;)
+        ''' Gets or sets the HTML emitted after generated worksheet content.
         ''' </summary>
-        ''' <returns></returns>
         Public Property HtmlDocumentEnd As String
 
         ''' <summary>
-        ''' Typically html+head tags
+        ''' Gets the default HTML document header.
         ''' </summary>
-        ''' <returns></returns>
         Protected Friend ReadOnly Property DefaultHtmlDocumentHeader As String =
             "<!doctype html><html><head>" & ControlChars.CrLf &
             "<meta http-equiv=""X-UA-Compatible"" content=""IE=edge"">" & ControlChars.CrLf &
             "<meta name=""viewport"" content=""width=device-width,initial-scale=1"">"
 
         ''' <summary>
-        ''' Typically /head+body tags
+        ''' Gets the default HTML fragment that closes HEAD and opens BODY.
         ''' </summary>
-        ''' <returns></returns>
         Protected Friend ReadOnly Property DefaultHtmlDocumentHeaderEndAndBeginOfBody As String = "</head><body>"
 
         ''' <summary>
-        ''' Typically /body+/html tags
+        ''' Gets the default HTML document ending.
         ''' </summary>
-        ''' <returns></returns>
         Protected Friend ReadOnly Property DefaultHtmlDocumentEnd As String = "</body></html>"
 
         ''' <summary>
-        ''' Typically some HTML indicating there was no content in Excel worksheet
+        ''' Gets the default HTML emitted for an empty worksheet.
         ''' </summary>
-        ''' <returns></returns>
         Protected Friend ReadOnly Property DefaultHtmlForEmptySheet As String = "-/-"
 
         ''' <summary>
-        ''' Typically some HTML indicating there was no content in Excel worksheet
+        ''' Gets the effective HTML emitted for an empty worksheet.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>Configured empty-sheet HTML, or the default empty-sheet HTML when no value is configured.</returns>
         Public Overridable Function EffectiveHtmlForEmptySheet() As String
             If HtmlForEmptySheet Is Nothing Then
                 Return DefaultHtmlForEmptySheet
@@ -105,9 +143,9 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' Typically /head+body tags
+        ''' Gets the effective HTML fragment that closes HEAD and opens BODY.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>Configured header/body transition HTML, or the default transition HTML when no value is configured.</returns>
         Public Overridable Function EffectiveHtmlDocumentHeaderEndAndBeginOfBody() As String
             If HtmlDocumentHeaderEndAndBeginOfBody Is Nothing Then
                 Return DefaultHtmlDocumentHeaderEndAndBeginOfBody
@@ -117,9 +155,9 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' Typically html+head+styles+body tags
+        ''' Gets the effective HTML document header including styles and BODY start.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>HTML emitted before worksheet content.</returns>
         Public Overridable Function EffectiveHtmlDocumentHeaderAndBody() As String
             Dim sb As New System.Text.StringBuilder(1024)
             sb.AppendLine(Me.EffectiveHtmlDocumentHeader)
@@ -129,9 +167,9 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' Typically html+head tags
+        ''' Gets the effective HTML document header.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>Configured document header HTML, or the default document header HTML when no value is configured.</returns>
         Public Overridable Function EffectiveHtmlDocumentHeader() As String
             If HtmlDocumentHeader Is Nothing Then
                 Return DefaultHtmlDocumentHeader
@@ -141,9 +179,9 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' Typically /body+/html tags
+        ''' Gets the effective HTML document ending.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>Configured document end HTML, or the default document end HTML when no value is configured.</returns>
         Public Overridable Function EffectiveHtmlDocumentEnd() As String
             If HtmlDocumentEnd Is Nothing Then
                 Return DefaultHtmlDocumentEnd
@@ -153,9 +191,9 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' Style HTML for the table (&lt;style&gt;...&lt;/style&gt;)
+        ''' Gets the effective STYLE element for generated worksheet tables.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>HTML STYLE element for generated worksheet tables.</returns>
         Public Overridable Function EffectiveTableCssClassStyleHtml() As String
             Dim sb As New System.Text.StringBuilder(1024)
             sb.AppendLine("<style>")
@@ -167,11 +205,11 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' Öffnenden Wrapper für ein Sheet ausgeben.
+        ''' Generates the opening HTML section wrapper for a worksheet.
         ''' </summary>
-        ''' <param name="anchorName"></param>
-        ''' <param name="sb"></param>
-        ''' <param name="visible">Sichtbar: True -> dieses Sheet ist initial sichtbar.</param>
+        ''' <param name="sb">String builder receiving generated HTML.</param>
+        ''' <param name="anchorName">Section ID and anchor name for the worksheet.</param>
+        ''' <param name="visible"><see langword="True"/> to mark the worksheet section as initially visible; otherwise, <see langword="False"/>.</param>
         Public Overridable Sub GenerateBeginSheetSection(sb As StringBuilder, anchorName As String, Optional visible As Boolean = False)
             If String.IsNullOrWhiteSpace(anchorName) Then Throw New ArgumentNullException(NameOf(anchorName))
             Dim visibleClass As String = If(visible, " cm-visible", String.Empty)
@@ -187,12 +225,16 @@ Namespace ExcelOps
             sb.AppendLine()
         End Sub
 
+        ''' <summary>
+        ''' Gets or sets the CSS class name used for generated worksheet titles.
+        ''' </summary>
         Public Property WorksheetTitleCssClassName As String = "cm-wb-sheet-title"
 
         ''' <summary>
-        ''' Öffnenden Wrapper für ein Sheet ausgeben.
+        ''' Generates the worksheet title HTML.
         ''' </summary>
-        ''' <param name="sb"></param>
+        ''' <param name="sb">String builder receiving generated HTML.</param>
+        ''' <param name="title">Worksheet title to render.</param>
         Public Overridable Sub GenerateSheetSectionTitle(sb As StringBuilder, title As String)
             If Me.ExportSheetNameAsTitle = SheetTitleStyles.None Then Return
             Dim TagName As String = Me.ExportSheetNameAsTitle.ToString
@@ -205,8 +247,9 @@ Namespace ExcelOps
         End Sub
 
         ''' <summary>
-        ''' Schließenden Wrapper für ein Sheet ausgeben.
+        ''' Generates the closing HTML section wrapper for a worksheet.
         ''' </summary>
+        ''' <param name="sb">String builder receiving generated HTML.</param>
         Public Overridable Sub GenerateEndSheetSection(sb As StringBuilder)
             sb.Append("</section>").AppendLine.AppendLine()
         End Sub
diff --git a/ExcelOps/ExcelOpsLowLevel/HtmlWorkbookExportOptions.vb b/ExcelOps/ExcelOpsLowLevel/HtmlWorkbookExportOptions.vb
index ee36110..9784add 100644
--- a/ExcelOps/ExcelOpsLowLevel/HtmlWorkbookExportOptions.vb
+++ b/ExcelOps/ExcelOpsLowLevel/HtmlWorkbookExportOptions.vb
@@ -7,86 +7,91 @@ Imports System.Text
 Namespace ExcelOps
 
 #Disable Warning CA1805 ' Keine unnötige Initialisierung
+    ''' <summary>
+    ''' Defines options for exporting a workbook to HTML.
+    ''' </summary>
     Public Class HtmlWorkbookExportOptions
         Inherits HtmlSheetExportOptions
 
+        ''' <summary>
+        ''' Creates a new HTML workbook export options instance.
+        ''' </summary>
         Public Sub New()
             MyBase.New
         End Sub
 
+        ''' <summary>
+        ''' Defines where workbook sheet navigation is rendered.
+        ''' </summary>
         Public Enum SheetNavigationPositions As Byte
             ''' <summary>
-            ''' No code for navigation embedded (must be added afterwards)
+            ''' Does not render workbook sheet navigation.
             ''' </summary>
             None = 0
             ''' <summary>
-            ''' Code for navigation at top
+            ''' Renders workbook sheet navigation before exported sheets.
             ''' </summary>
             Top = 1
             ''' <summary>
-            ''' Code for navigation as bottom
+            ''' Renders workbook sheet navigation after exported sheets.
             ''' </summary>
             Bottom = 2
         End Enum
 
         ''' <summary>
-        ''' Display style of navigation
+        ''' Gets or sets where workbook sheet navigation is rendered.
         ''' </summary>
-        ''' <returns></returns>
         Public Property SheetNavigationPosition As SheetNavigationPositions = SheetNavigationPositions.Top
 
+        ''' <summary>
+        ''' Defines how workbook sheet navigation links behave.
+        ''' </summary>
         Public Enum SheetNavigationActionStyles As Byte
             ''' <summary>
-            ''' All sheets are always visible (ignores selected sheet of Excel workbook)
+            ''' Keeps all exported sheets visible and navigates by anchor links.
             ''' </summary>
             JumpToAnchor = 0
             ''' <summary>
-            ''' Only the selected sheet is visible
+            ''' Shows only the selected sheet and switches visible sheet sections by script.
             ''' </summary>
             SwitchVisibleSheet = 1
         End Enum
 
         ''' <summary>
-        ''' Display style of navigation
+        ''' Gets or sets how workbook sheet navigation links behave.
         ''' </summary>
-        ''' <returns></returns>
         Public Property SheetNavigationActionStyle As SheetNavigationActionStyles = SheetNavigationActionStyles.JumpToAnchor
 
         ''' <summary>
-        ''' Always show navigation while scrolling
+        ''' Gets or sets whether workbook sheet navigation remains visible while scrolling.
         ''' </summary>
-        ''' <returns></returns>
         Public Property SheetNavigationAlwaysVisible As Boolean = False
 
         ''' <summary>
-        ''' Export all sheets or visible sheets only
+        ''' Gets or sets whether hidden workbook sheets are exported.
         ''' </summary>
-        ''' <returns></returns>
         Public Property ExportHiddenSheets As Boolean = False
 
         ''' <summary>
-        ''' Export chart sheets
+        ''' Gets or sets whether chart sheets are exported.
         ''' </summary>
-        ''' <returns></returns>
         Public Property ExportChartSheets As Boolean = False
 
         ''' <summary>
-        ''' Export work sheets
+        ''' Gets or sets whether worksheets are exported.
         ''' </summary>
-        ''' <returns></returns>
         Public Property ExportWorkSheets As Boolean = True
 
 
         ''' <summary>
-        ''' The CSS class name for the worksheets navigation
+        ''' Gets or sets the CSS class name used for workbook sheet navigation.
         ''' </summary>
-        ''' <returns></returns>
         Public Property WorksheetsNavigationCssClassName As String = "cm-wb-subnav"
 
         ''' <summary>
-        ''' Style HTML for the table (&lt;style&gt;...&lt;/style&gt;)
+        ''' Gets the effective STYLE element for workbook sheet navigation.
         ''' </summary>
-        ''' <returns></returns>
+        ''' <returns>HTML STYLE element for workbook sheet navigation.</returns>
         Public Overridable Function EffectiveWorksheetsNavigationCssStyleHtml() As String
             Dim sb As New System.Text.StringBuilder(1024)
             sb.AppendLine("<style>")
@@ -107,10 +112,9 @@ Namespace ExcelOps
             Return sb.ToString
         End Function
 
-        ''' <summary>
-        ''' Typically html+head+styles+body tags
-        ''' </summary>
-        ''' <returns></returns>
+        ''' <inheritdoc/>
+        ''' <returns>HTML emitted before workbook sheet content.</returns>
+        ''' <remarks>Adds workbook sheet navigation styles to the base HTML document header.</remarks>
         Public Overrides Function EffectiveHtmlDocumentHeaderAndBody() As String
             Dim sb As New System.Text.StringBuilder(1024)
             sb.AppendLine(Me.EffectiveHtmlDocumentHeader)
@@ -121,17 +125,16 @@ Namespace ExcelOps
         End Function
 
         ''' <summary>
-        ''' The ID attribute value for the NAV tag
+        ''' Gets or sets the ID attribute value used for the workbook sheet navigation element.
         ''' </summary>
-        ''' <returns></returns>
         Public Property WorksheetsNavigationTagId As String = "workbook-nav"
 
         ''' <summary>
-        ''' Generate the HTML code for a worksheet navigation
+        ''' Generates workbook sheet navigation HTML.
         ''' </summary>
-        ''' <param name="sb"></param>
-        ''' <param name="items">Labels for the several worksheets (typically worksheet names)</param>
-        ''' <param name="options"></param>
+        ''' <param name="sb">String builder receiving generated HTML.</param>
+        ''' <param name="items">Navigation labels, typically worksheet names.</param>
+        ''' <param name="options">Workbook export options controlling navigation output.</param>
         Public Overridable Sub GenerateWorkbookSubNavigation(sb As StringBuilder,
                                              items As IEnumerable(Of String),
                                              options As HtmlWorkbookExportOptions)
@@ -139,12 +142,12 @@ Namespace ExcelOps
         End Sub
 
         ''' <summary>
-        ''' Generate the HTML code for a worksheet navigation
+        ''' Generates workbook sheet navigation HTML.
         ''' </summary>
-        ''' <param name="sb"></param>
-        ''' <param name="navigationItemTitles">Labels for the several worksheets (typically worksheet names)</param>
-        ''' <param name="options"></param>
-        ''' <param name="anchorNames">Section/anchor names for the several worksheets</param>
+        ''' <param name="sb">String builder receiving generated HTML.</param>
+        ''' <param name="navigationItemTitles">Navigation labels, typically worksheet names.</param>
+        ''' <param name="anchorNames">Section IDs and anchor names for the worksheets.</param>
+        ''' <param name="options">Workbook export options controlling navigation output.</param>
         Public Overridable Sub GenerateWorkbookSubNavigation(sb As StringBuilder,
                                              navigationItemTitles As IEnumerable(Of String),
                                              anchorNames As IEnumerable(Of String),
diff --git a/ExcelOps/Exceptions/BinaryXlsFileNotSupportedException.vb b/ExcelOps/Exceptions/BinaryXlsFileNotSupportedException.vb
new file mode 100644
index 0000000..358d745
--- /dev/null
+++ b/ExcelOps/Exceptions/BinaryXlsFileNotSupportedException.vb
@@ -0,0 +1,47 @@
+Namespace ExcelOps
+#Disable Warning CA2237 ' Mark ISerializable types with serializable
+#Disable Warning CA1032 ' Implement standard exception constructors
+    ''' <summary>
+    ''' An exception which is thrown when a binary Excel workbook cannot be opened by the selected engine.
+    ''' </summary>
+    Public Class BinaryXlsFileNotSupportedException
+#Enable Warning CA1032 ' Implement standard exception constructors
+#Enable Warning CA2237 ' Mark ISerializable types with serializable
+        Inherits FileCorruptedOrInvalidFileFormatException
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary Excel workbook.
+        ''' </summary>
+        ''' <param name="filePath">Path of the affected file.</param>
+        Public Sub New(filePath As String)
+            MyBase.New(filePath)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary Excel workbook.
+        ''' </summary>
+        ''' <param name="filePath">Path of the affected file.</param>
+        ''' <param name="innerException">Original exception that caused this exception.</param>
+        Public Sub New(filePath As String, innerException As Exception)
+            MyBase.New(filePath, innerException)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary Excel workbook.
+        ''' </summary>
+        ''' <param name="file">Affected file.</param>
+        Public Sub New(file As System.IO.FileInfo)
+            Me.New(file.FullName)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary Excel workbook.
+        ''' </summary>
+        ''' <param name="file">Affected file.</param>
+        ''' <param name="innerException">Original exception that caused this exception.</param>
+        Public Sub New(file As System.IO.FileInfo, innerException As Exception)
+            Me.New(file.FullName, innerException)
+        End Sub
+
+    End Class
+End Namespace
diff --git a/ExcelOps/Exceptions/BinaryXlsbFileNotSupportedException.vb b/ExcelOps/Exceptions/BinaryXlsbFileNotSupportedException.vb
new file mode 100644
index 0000000..22e9c9e
--- /dev/null
+++ b/ExcelOps/Exceptions/BinaryXlsbFileNotSupportedException.vb
@@ -0,0 +1,47 @@
+Namespace ExcelOps
+#Disable Warning CA2237 ' Mark ISerializable types with serializable
+#Disable Warning CA1032 ' Implement standard exception constructors
+    ''' <summary>
+    ''' An exception which is thrown when a binary XLSB workbook cannot be opened by the selected engine.
+    ''' </summary>
+    Public Class BinaryXlsbFileNotSupportedException
+#Enable Warning CA1032 ' Implement standard exception constructors
+#Enable Warning CA2237 ' Mark ISerializable types with serializable
+        Inherits FileCorruptedOrInvalidFileFormatException
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary XLSB workbook.
+        ''' </summary>
+        ''' <param name="filePath">Path of the affected file.</param>
+        Public Sub New(filePath As String)
+            MyBase.New(filePath)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary XLSB workbook.
+        ''' </summary>
+        ''' <param name="filePath">Path of the affected file.</param>
+        ''' <param name="innerException">Original exception that caused this exception.</param>
+        Public Sub New(filePath As String, innerException As Exception)
+            MyBase.New(filePath, innerException)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary XLSB workbook.
+        ''' </summary>
+        ''' <param name="file">Affected file.</param>
+        Public Sub New(file As System.IO.FileInfo)
+            Me.New(file.FullName)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for an unsupported binary XLSB workbook.
+        ''' </summary>
+        ''' <param name="file">Affected file.</param>
+        ''' <param name="innerException">Original exception that caused this exception.</param>
+        Public Sub New(file As System.IO.FileInfo, innerException As Exception)
+            Me.New(file.FullName, innerException)
+        End Sub
+
+    End Class
+End Namespace
diff --git a/ExcelOps/Exceptions/FilePasswordProtectedMismatchException.vb b/ExcelOps/Exceptions/FilePasswordProtectedMismatchException.vb
new file mode 100644
index 0000000..e10980d
--- /dev/null
+++ b/ExcelOps/Exceptions/FilePasswordProtectedMismatchException.vb
@@ -0,0 +1,47 @@
+Namespace ExcelOps
+#Disable Warning CA2237 ' Mark ISerializable types with serializable
+#Disable Warning CA1032 ' Implement standard exception constructors
+    ''' <summary>
+    ''' An exception which is thrown when a password-protected workbook cannot be opened with the supplied password.
+    ''' </summary>
+    Public Class FilePasswordProtectedMismatchException
+#Enable Warning CA1032 ' Implement standard exception constructors
+#Enable Warning CA2237 ' Mark ISerializable types with serializable
+        Inherits FileCorruptedOrInvalidFileFormatException
+
+        ''' <summary>
+        ''' Creates an exception for a password-protected workbook.
+        ''' </summary>
+        ''' <param name="filePath">Path of the affected file.</param>
+        Public Sub New(filePath As String)
+            MyBase.New(filePath)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for a password-protected workbook.
+        ''' </summary>
+        ''' <param name="filePath">Path of the affected file.</param>
+        ''' <param name="innerException">Original exception that caused this exception.</param>
+        Public Sub New(filePath As String, innerException As Exception)
+            MyBase.New(filePath, innerException)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for a password-protected workbook.
+        ''' </summary>
+        ''' <param name="file">Affected file.</param>
+        Public Sub New(file As System.IO.FileInfo)
+            Me.New(file.FullName)
+        End Sub
+
+        ''' <summary>
+        ''' Creates an exception for a password-protected workbook.
+        ''' </summary>
+        ''' <param name="file">Affected file.</param>
+        ''' <param name="innerException">Original exception that caused this exception.</param>
+        Public Sub New(file As System.IO.FileInfo, innerException As Exception)
+            Me.New(file.FullName, innerException)
+        End Sub
+
+    End Class
+End Namespace
diff --git a/ExcelOpsTest-FreeSpireXls/TestExcelOps-FreeSpireXls.vbproj b/ExcelOpsTest-FreeSpireXls/TestExcelOps-FreeSpireXls.vbproj
index 5684240..9db78de 100644
--- a/ExcelOpsTest-FreeSpireXls/TestExcelOps-FreeSpireXls.vbproj
+++ b/ExcelOpsTest-FreeSpireXls/TestExcelOps-FreeSpireXls.vbproj
@@ -33,6 +33,12 @@
     <None Remove="test_data\SampleTable01.xlsx" />
     <None Remove="test_data\StructuralChangesFormulaReferences.xlsx" />
     <None Remove="test_data\VbaProject.xlsm" />
+    <None Remove="test_data\WorkbookNoPassword.xls" />
+    <None Remove="test_data\WorkbookNoPassword.xlsb" />
+    <None Remove="test_data\WorkbookNoPassword.xlsx" />
+    <None Remove="test_data\WorkbookPasswordProtected.xls" />
+    <None Remove="test_data\WorkbookPasswordProtected.xlsb" />
+    <None Remove="test_data\WorkbookPasswordProtected.xlsx" />
   </ItemGroup>
 
   <ItemGroup>
@@ -90,6 +96,24 @@
     <Content Include="test_data\VbaProject.xlsm">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="test_data\WorkbookNoPassword.xls">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookNoPassword.xlsb">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookNoPassword.xlsx">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookPasswordProtected.xls">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookPasswordProtected.xlsb">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookPasswordProtected.xlsx">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
   </ItemGroup>
 
   <ItemGroup>
diff --git a/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xls b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xls
new file mode 100644
index 0000000..817d43f
Binary files /dev/null and b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xls differ
diff --git a/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xlsb b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xlsb
new file mode 100644
index 0000000..85b682e
Binary files /dev/null and b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xlsb differ
diff --git a/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xlsx b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xlsx
new file mode 100644
index 0000000..571454c
Binary files /dev/null and b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookNoPassword.xlsx differ
diff --git a/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xls b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xls
new file mode 100644
index 0000000..1a46ccb
Binary files /dev/null and b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xls differ
diff --git a/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xlsb b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xlsb
new file mode 100644
index 0000000..9a3c9d7
Binary files /dev/null and b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xlsb differ
diff --git a/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xlsx b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xlsx
new file mode 100644
index 0000000..4a368ff
Binary files /dev/null and b/ExcelOpsTest-FreeSpireXls/test_data/WorkbookPasswordProtected.xlsx differ
diff --git a/ExcelOpsTest-SpireXls/TestExcelOps-SpireXls.vbproj b/ExcelOpsTest-SpireXls/TestExcelOps-SpireXls.vbproj
index 6cc9381..2844637 100644
--- a/ExcelOpsTest-SpireXls/TestExcelOps-SpireXls.vbproj
+++ b/ExcelOpsTest-SpireXls/TestExcelOps-SpireXls.vbproj
@@ -33,6 +33,12 @@
     <None Remove="test_data\SampleTable01.xlsx" />
     <None Remove="test_data\StructuralChangesFormulaReferences.xlsx" />
     <None Remove="test_data\VbaProject.xlsm" />
+    <None Remove="test_data\WorkbookNoPassword.xls" />
+    <None Remove="test_data\WorkbookNoPassword.xlsb" />
+    <None Remove="test_data\WorkbookNoPassword.xlsx" />
+    <None Remove="test_data\WorkbookPasswordProtected.xls" />
+    <None Remove="test_data\WorkbookPasswordProtected.xlsb" />
+    <None Remove="test_data\WorkbookPasswordProtected.xlsx" />
   </ItemGroup>
 
   <ItemGroup>
@@ -90,6 +96,24 @@
     <Content Include="test_data\VbaProject.xlsm">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="test_data\WorkbookNoPassword.xls">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookNoPassword.xlsb">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookNoPassword.xlsx">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookPasswordProtected.xls">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookPasswordProtected.xlsb">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="test_data\WorkbookPasswordProtected.xlsx">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
   </ItemGroup>
 
   <ItemGroup>
diff --git a/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xls b/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xls
new file mode 100644
index 0000000..817d43f
Binary files /dev/null and b/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xls differ
diff --git a/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xlsb b/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xlsb
new file mode 100644
index 0000000..85b682e
Binary files /dev/null and b/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xlsb differ
diff --git a/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xlsx b/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xlsx
new file mode 100644
index 0000000..571454c
Binary files /dev/null and b/ExcelOpsTest-SpireXls/test_data/WorkbookNoPassword.xlsx differ
diff --git a/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xls b/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xls
new file mode 100644
index 0000000..1a46ccb
Binary files /dev/null and b/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xls differ
diff --git a/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xlsb b/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xlsb
new file mode 100644
index 0000000..9a3c9d7
Binary files /dev/null and b/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xlsb differ
diff --git a/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xlsx b/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xlsx
new file mode 100644
index 0000000..4a368ff
Binary files /dev/null and b/ExcelOpsTest-SpireXls/test_data/WorkbookPasswordProtected.xlsx differ
diff --git a/ExcelOpsTest/ExcelOpsTests.Engines/ExcelOpsTestBase.vb b/ExcelOpsTest/ExcelOpsTests.Engines/ExcelOpsTestBase.vb
index 0acbb43..261eaa6 100644
--- a/ExcelOpsTest/ExcelOpsTests.Engines/ExcelOpsTestBase.vb
+++ b/ExcelOpsTest/ExcelOpsTests.Engines/ExcelOpsTestBase.vb
@@ -366,26 +366,87 @@ Namespace ExcelOpsTests.Engines
 
         <Test> Public Sub PasswordForOpening()
             Dim Wb As T
-            'Testfile without password
-            Dim TestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "ExcelOpsGrund01.xlsx")
+            'Testfile without password.
+            Dim TestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "WorkbookNoPassword.xlsx")
             Wb = Me.CreateInstance(TestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly))
-            ClassicAssert.AreEqual("Grunddaten", Wb.SheetNames(0))
+            ClassicAssert.Greater(Wb.SheetNames.Count, 0)
+            Wb.Close()
 
-            'Now, save it with password
-            Wb.PasswordForOpening = "dummy"
-            Dim NewXlsxTargetPath As String = TestEnvironment.FullPathOfDynTestFile(Wb, "PasswordProtectedFile.xlsx")
-            Wb.SaveAs(NewXlsxTargetPath, ExcelDataOperationsBase.SaveOptionsForDisabledCalculationEngines.DefaultBehaviour)
-            'Console.WriteLine("Saved password protected file to: " & NewXlsxTargetPath)
+            Dim PasswordProtectedTestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "WorkbookPasswordProtected.xlsx")
+
+            'Try to reload it without password -> it must fail.
+            ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "something else")))
+            ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "")))
+            ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, Nothing)))
+            Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "test"))
+            ClassicAssert.Greater(Wb.SheetNames.Count, 0)
             Wb.Close()
 
-            'Try to reload it without password -> it must fail
-            ClassicAssert.Catch(Of Exception)(Sub() Wb = Me.CreateInstance(NewXlsxTargetPath, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "something else")))
-            ClassicAssert.Catch(Of Exception)(Sub() Wb = Me.CreateInstance(NewXlsxTargetPath, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "")))
-            ClassicAssert.Catch(Of Exception)(Sub() Wb = Me.CreateInstance(NewXlsxTargetPath, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, Nothing)))
+        End Sub
+
+        <Test> Public Sub PasswordForOpeningXls()
+            Dim Wb As T
+            Dim PasswordProtectedTestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "WorkbookPasswordProtected.xls")
+
+            Select Case Me.CreateInstanceUninitialized().EngineName
+                Case "Epplus 4 (LGPL)", "Epplus (Polyform license edition)"
+                    ClassicAssert.Throws(Of BinaryXlsFileNotSupportedException)(Sub() Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "something else")))
+                    ClassicAssert.Throws(Of BinaryXlsFileNotSupportedException)(Sub() Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "")))
+                    ClassicAssert.Throws(Of BinaryXlsFileNotSupportedException)(Sub() Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, Nothing)))
+                    ClassicAssert.Throws(Of BinaryXlsFileNotSupportedException)(Sub() Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "test")))
+                Case Else
+                    ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "something else")))
+                    ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "")))
+                    ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, Nothing)))
+                    Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "test"))
+                    ClassicAssert.Greater(Wb.SheetNames.Count, 0)
+                    Wb.Close()
+            End Select
+
+        End Sub
+
+        <Test> Public Sub PasswordForOpeningXlsb()
+            Dim Wb As T
+            'Testfile without password.
+            Dim TestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "WorkbookNoPassword.xlsb")
 
-            'Reload it with password -> now it must succeed
-            Wb = Me.CreateInstance(NewXlsxTargetPath, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "dummy"))
-            ClassicAssert.AreEqual("Grunddaten", Wb.SheetNames(0))
+            Select Case Me.CreateInstanceUninitialized().EngineName
+                Case "Epplus 4 (LGPL)", "Epplus (Polyform license edition)"
+                    ClassicAssert.Throws(Of BinaryXlsbFileNotSupportedException)(Sub() Me.CreateInstance(TestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly)))
+                Case Else
+                    Wb = Me.CreateInstance(TestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly))
+                    ClassicAssert.Greater(Wb.SheetNames.Count, 0)
+                    Wb.Close()
+            End Select
+
+            Dim PasswordProtectedTestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "WorkbookPasswordProtected.xlsb")
+
+            'Try to reload it without password -> it must fail.
+            ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "something else")))
+            ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "")))
+            ClassicAssert.Catch(Of FilePasswordProtectedMismatchException)(Sub() Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, Nothing)))
+            Select Case Me.CreateInstanceUninitialized().EngineName
+                Case "Epplus 4 (LGPL)", "Epplus (Polyform license edition)"
+                    ClassicAssert.Throws(Of BinaryXlsbFileNotSupportedException)(Sub() Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "test")))
+                Case Else
+                    Wb = Me.CreateInstance(PasswordProtectedTestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly, "test"))
+                    ClassicAssert.Greater(Wb.SheetNames.Count, 0)
+                    Wb.Close()
+            End Select
+
+        End Sub
+
+        <Test> Public Sub BinaryXlsFileNotSupported()
+            Dim Wb As T
+            Dim TestFile As String = TestEnvironment.FullPathOfExistingTestFile("test_data", "WorkbookNoPassword.xls")
+
+            Select Case Me.CreateInstanceUninitialized().EngineName
+                Case "Epplus 4 (LGPL)", "Epplus (Polyform license edition)"
+                    ClassicAssert.Throws(Of BinaryXlsFileNotSupportedException)(Sub() Me.CreateInstance(TestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly)))
+                Case Else
+                    Wb = Me.CreateInstance(TestFile, ExcelOps.ExcelDataOperationsBase.OpenMode.OpenExistingFile, New ExcelDataOperationsOptions(ExcelDataOperationsOptions.WriteProtectionMode.ReadOnly))
+                    ClassicAssert.Greater(Wb.SheetNames.Count, 0)
+            End Select
         End Sub
 
         <Test> Public Sub CreateWorkbookWithoutFilePath()
diff --git a/ExcelOpsTest/test_data/WorkbookNoPassword.xls b/ExcelOpsTest/test_data/WorkbookNoPassword.xls
new file mode 100644
index 0000000..817d43f
Binary files /dev/null and b/ExcelOpsTest/test_data/WorkbookNoPassword.xls differ
diff --git a/ExcelOpsTest/test_data/WorkbookNoPassword.xlsb b/ExcelOpsTest/test_data/WorkbookNoPassword.xlsb
new file mode 100644
index 0000000..85b682e
Binary files /dev/null and b/ExcelOpsTest/test_data/WorkbookNoPassword.xlsb differ
diff --git a/ExcelOpsTest/test_data/WorkbookNoPassword.xlsx b/ExcelOpsTest/test_data/WorkbookNoPassword.xlsx
new file mode 100644
index 0000000..571454c
Binary files /dev/null and b/ExcelOpsTest/test_data/WorkbookNoPassword.xlsx differ
diff --git a/ExcelOpsTest/test_data/WorkbookPasswordProtected.xls b/ExcelOpsTest/test_data/WorkbookPasswordProtected.xls
new file mode 100644
index 0000000..1a46ccb
Binary files /dev/null and b/ExcelOpsTest/test_data/WorkbookPasswordProtected.xls differ
diff --git a/ExcelOpsTest/test_data/WorkbookPasswordProtected.xlsb b/ExcelOpsTest/test_data/WorkbookPasswordProtected.xlsb
new file mode 100644
index 0000000..9a3c9d7
Binary files /dev/null and b/ExcelOpsTest/test_data/WorkbookPasswordProtected.xlsb differ
diff --git a/ExcelOpsTest/test_data/WorkbookPasswordProtected.xlsx b/ExcelOpsTest/test_data/WorkbookPasswordProtected.xlsx
new file mode 100644
index 0000000..4a368ff
Binary files /dev/null and b/ExcelOpsTest/test_data/WorkbookPasswordProtected.xlsx differ
diff --git a/README.md b/README.md
index 6753858..ccf5ce2 100644
--- a/README.md
+++ b/README.md
@@ -230,3 +230,14 @@ leads to following output
 ```
 </details>
 
+## File format support by engine
+
+The following table summarizes the expected behavior when opening static test workbooks with or without a password. Password-protected test workbooks use `test` as the valid password.
+
+| Engine | `.xlsx` without password | `.xlsx` with missing/wrong password | `.xlsx` with correct password | `.xls` without password | `.xls` with missing/wrong password | `.xls` with correct password | `.xlsb` without password | `.xlsb` with missing/wrong password | `.xlsb` with correct password |
+|---|---|---|---|---|---|---|---|---|---|
+| Microsoft Excel | Supported | `FilePasswordProtectedMismatchException` | Supported | Supported | `FilePasswordProtectedMismatchException` | Supported | Supported | `FilePasswordProtectedMismatchException` | Supported |
+| EPPlus 4 / Free FixCalcs | Supported | `FilePasswordProtectedMismatchException` | Supported | `BinaryXlsFileNotSupportedException` | `BinaryXlsFileNotSupportedException` | `BinaryXlsFileNotSupportedException` | `BinaryXlsbFileNotSupportedException` | `FilePasswordProtectedMismatchException` | `BinaryXlsbFileNotSupportedException` |
+| EPPlus Polyform | Supported | `FilePasswordProtectedMismatchException` | Supported | `BinaryXlsFileNotSupportedException` | `BinaryXlsFileNotSupportedException` | `BinaryXlsFileNotSupportedException` | `BinaryXlsbFileNotSupportedException` | `FilePasswordProtectedMismatchException` | `BinaryXlsbFileNotSupportedException` |
+| Spire.Xls | Supported | `FilePasswordProtectedMismatchException` | Supported | Supported | `FilePasswordProtectedMismatchException` | Supported | Supported | `FilePasswordProtectedMismatchException` | Supported |
+| FreeSpire.Xls | Supported | `FilePasswordProtectedMismatchException` | Supported | Supported | `FilePasswordProtectedMismatchException` | Supported | Supported | `FilePasswordProtectedMismatchException` | Supported |
diff --git a/tools/check-api-docs.ps1 b/tools/check-api-docs.ps1
index f4f3611..8794200 100644
--- a/tools/check-api-docs.ps1
+++ b/tools/check-api-docs.ps1
@@ -21,16 +21,7 @@ $sourceRoots = @(
 
 $excludedDocumentationScopes = @(
     "Epplus-FixCalcsEdition/EPPlus/",
-    "TestAndDemoExcelOps/",
-    "ExcelOps/ExcelOpsLowLevel/HtmlSheetExportOptions.vb",
-    "ExcelOps/ExcelOpsLowLevel/HtmlWorkbookExportOptions.vb"
-)
-
-$excludedDocumentationDeclarations = @(
-    @{
-        File = "ExcelOps/ExcelOpsLowLevel/ExcelDataOperationsBase.vb"
-        Pattern = "^\s*Public\s+Enum\s+HtmlDocumentExportParts\b"
-    }
+    "TestAndDemoExcelOps/"
 )
 
 $maxMissingDocumentation = 0
@@ -75,18 +66,6 @@ function Test-Inheritdoc([System.Collections.Generic.List[string]] $docBlock) {
     return (($docBlock -join "`n") -match "<inheritdoc\s*/>")
 }
 
-function Test-ExcludedDocumentationDeclaration([string] $relativeFile, [string] $declaration) {
-    $normalizedFile = $relativeFile.Replace("\", "/")
-    foreach ($excludedDeclaration in $excludedDocumentationDeclarations) {
-        if ($normalizedFile.Equals($excludedDeclaration.File, [System.StringComparison]::OrdinalIgnoreCase) -and
-            $declaration -match $excludedDeclaration.Pattern) {
-            return $true
-        }
-    }
-
-    return $false
-}
-
 $files = New-Object System.Collections.Generic.List[string]
 foreach ($sourceRoot in $sourceRoots) {
     $rootPath = Join-Path $repoRoot $sourceRoot
@@ -144,10 +123,6 @@ foreach ($file in $files) {
         $docBlock = Get-XmlDocBlock $lines $i
         $declaration = $line.Trim()
 
-        if (Test-ExcludedDocumentationDeclaration $relativeFile $declaration) {
-            continue
-        }
-
         if (-not (Is-Documented $docBlock)) {
             $missingDocumentation.Add([pscustomobject]@{
                 File = $relativeFile