MBR2GPT error 0x000036B7

Run MBR2GPT offline from Windows Recovery Environment (WinRE) without /allowFullOS, because this allows it to reuse a suitable existing system partition instead of always shrinking the active Windows partition to create a new EFI System Partition (ESP).^1^

Convert from WinRE

Back up important files first. A successful conversion changes the disk layout, and the PC must subsequently boot in UEFI mode.

1. Confirm that the computer’s firmware supports UEFI.
2. Enter WinRE using Windows installation media and open Command Prompt. This is the accepted resolution in matching 0x000036B7 cases.^2^
3. Identify the Windows system disk:

diskpart
list disk
list volume
exit

4. Substitute the correct disk number below—commonly 0, but do not assume—and validate it:

mbr2gpt /validate /disk:0

5. If validation completes successfully, perform the conversion:

mbr2gpt /convert /disk:0

Do not add /allowFullOS while running in WinRE. In full Windows, the existing MBR system partition is in use and cannot be repurposed, so MBR2GPT must shrink the OS partition and create a new ESP. Offline, it can reuse the existing system partition when that partition is suitable.^1^

6. Only after the command reports Conversion completed successfully, restart into firmware settings and change the boot mode from Legacy/CSM to UEFI. Microsoft’s checklist also specifies disabling CSM; verify the result afterward by opening msinfo32 and checking that BIOS Mode reports UEFI.^3^

If conversion still reports 0x000036B7

This error occurs while MBR2GPT is trying to create the EFI System Partition. Inspect the detailed logs rather than deleting or resizing partitions blindly. In WinRE/Windows PE, the default logs are under %windir%:

type %windir%\setuperr.log
notepad %windir%\setupact.log

The relevant files are setupact.log, setuperr.log, diagerr.xml, and diagwrn.xml; setupact.log and setuperr.log contain the most detailed disk-layout and conversion information.^1^

Check the last MBR2GPT entries for which condition failed:

• Partition count/layout: MBR2GPT requires no more than three primary MBR partitions and does not accept extended or logical partitions.
• System partition: One partition must be active and recognized as the system partition, with a valid default Windows entry in its BCD store.
• Disk-edge space: The disk needs space outside its partitions for GPT metadata.
• ESP creation: If the existing system partition cannot be reused, MBR2GPT must shrink the Windows partition to create a 100 MB FAT32 ESP, or 260 MB on a 4K-sector disk.
• Encryption: If BitLocker is enabled, suspend protection before conversion.

These are documented conversion prerequisites and ESP-creation rules.^1^

Do not delete a Recovery or System Reserved partition solely to make room. First identify the exact failed condition from setupact.log and capture the current layout:

diskpart
list disk
select disk 0
list partition
list volume
exit

If the log reports a format or disk I/O failure rather than an inability to shrink or reuse a partition, check the disk’s health before another conversion attempt; a matching Microsoft Q&A case notes that a format failure can indicate a bad disk.^2^

References

1. MBR2GPT.EXE
2. Cannot create EFI system partition. Error: 0x000036B7 when running mbr2gpt.exe - Microsoft Q&A
3. MBR2GPT tool test guidance