Dynamic Disk Recovery: Convert a Windows 11 Boot Drive from Dynamic to Basic Without Data Loss

Fix INACCESSIBLE_BOOT_DEVICE (0x7B), "Invalid dynamic pack", and IO1_INITIALIZATION_FAILED (0x69) after an accidental dynamic-disk conversion. Everything is done offline from an Ubuntu live USB, with no reinstall and no data loss.

⚠️ This is a real recovery from one machine. Check every partition number and sector offset against your disks, and back up first. Commands that write to disk are marked ⚠️.

The problem

While a USB stick was being wiped in Windows Disk Management, 9 drives, including the boot NVMe, were converted to dynamic disks (LDM). NIUBI Partition Editor Free was then used to convert one MBR disk back. It left a BootExecute hook (nb-fre) and an MDA_NTDRV driver service, and it broke the dynamic pack. Windows stopped booting.

Symptoms

Stage	Exact error
After the NIUBI conversion	INACCESSIBLE_BOOT_DEVICE (0x7B): volmgrx reports invalid dynamic pack
After the table and registry repairs	Long pause at the spinning dots, then IO1_INITIALIZATION_FAILED (0x69)
After sgdisk --sort	Boots. Drive letters shuffled, clock off by the UTC offset

Quick path

1. Back up partition tables and the first/last 1 MiB of every disk from a live USB → 02
2. GPT: sgdisk -t 3:0700 -d 1 (retype LDM data, delete LDM metadata) → 03
3. MBR: rewrite with sfdisk, keeping label-id, with one type-07 partition at the true NTFS start → 04
4. Registry (offline): restore BootExecute, delete the MDA_NTDRV service and volmgrx\PrimaryPackId, rewrite stale MountedDevices → 05
5. 0x69: close GPT numbering gaps with sgdisk --sort → 06
6. Verify read-only, reboot, clean up → 07, 08

Table of contents

• 01 · What happened
• 02 · Back up first
• 03 · Convert GPT dynamic disks
• 04 · Convert MBR dynamic disks
• 05 · Offline registry fixes
• 06 · Fix 0x69 (partition gaps)
• 07 · Verify before reboot
• 08 · After-boot cleanup
• 09 · Troubleshooting log
• 10 · What not to do
• FAQ · References and credits
• Scripts: backup · GUID → MountedDevices · read-only verify
• Machine-readable: llms.txt · data/recovery-steps.json

Credits

Written by Xoza Shadow, with help from his AI tech-support assistant, Patch. See references and credits. To cite this guide, see CITATION.cff.

Want your own AI tech-support assistant like Patch? Get the Patch · Tech Support bot template.

License

Docs: CC BY 4.0. Scripts are provided as-is; read them before running.