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Zachary-Cavanell's avatar
Zachary-Cavanell
Bronze Contributor
Apr 05, 2017

Shifting from BIOS to UEFI with the Windows 10 Creators Update MBR2GPT disk conversion tool

Comprehensive yet quick video overview that explains how you can safely and non-destructively convert a Windows 10 machine from legacy BIOS to UEFI disk partitioning; and how you can automate the con...
windows 10
Alex Chepurnoy's avatar
Alex Chepurnoy
Copper Contributor
Aug 01, 2018

I have been trying to use this converter for a few days now and always get stuck on 

MBR2GPT: Trying to shrink the OS partition

Here is the log:

2018-08-01 12:16:43, Info MBR2GPT was explicitly asked to run in full OS mode.
2018-08-01 12:16:43, Info MBR2GPT: Attempting to convert disk 0
2018-08-01 12:16:43, Info MBR2GPT: Retrieving layout of disk
2018-08-01 12:16:43, Info MBR2GPT: Initial partition information
2018-08-01 12:16:43, Info ===========================================================
2018-08-01 12:16:43, Info Partition layout for disk: 0
2018-08-01 12:16:43, Info Partition style : MBR
2018-08-01 12:16:43, Info MBR signature: 3030528643
2018-08-01 12:16:43, Info Number of partitions : 1
2018-08-01 12:16:43, Info ===================PARTITION===============================
2018-08-01 12:16:43, Info Number: 1
2018-08-01 12:16:43, Info Type: 7
2018-08-01 12:16:43, Info Boot: Yes
2018-08-01 12:16:43, Info Recognized: Yes
2018-08-01 12:16:43, Info Style: 0
2018-08-01 12:16:43, Info Offset: 1048576
2018-08-01 12:16:43, Info Length: 958046142464
2018-08-01 12:16:43, Info Volume: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 12:16:43, Info Drive: C:\
2018-08-01 12:16:43, Info NT Path: \Device\HardDisk0\Partition1
2018-08-01 12:16:43, Info ===========================================================
2018-08-01 12:16:43, Info ESP partition size will be 104857600
2018-08-01 12:16:43, Info MBR2GPT: Validating layout, disk sector size is: 512 bytes
2018-08-01 12:16:43, Info BCD: Opening store. Flags: 0x0
2018-08-01 12:16:43, Info BCD: Store path: "\??\GLOBALROOT\device\harddisk0\partition1\Boot\BCD"
2018-08-01 12:16:43, Info BCD: Loaded hive at BCD00000000
2018-08-01 12:16:43, Info BCD: Opening object {9dea862c-5cdd-4e70-acc1-f32b344d4795}
2018-08-01 12:16:43, Info FindOSPartitions: Default boot entry: {6B5EAFC2-954A-11E8-888E-001A7DDA7113}
2018-08-01 12:16:43, Info BCD: Opening object {6b5eafc2-954a-11e8-888e-001a7dda7113}
2018-08-01 12:16:43, Info VERBOSE: Device path: \Device\HarddiskVolume5
2018-08-01 12:16:43, Info VERBOSE: Dos path: \\?\GLOBALROOT\Device\HarddiskVolume5
2018-08-01 12:16:43, Info FindOSPartitions: Volume name for the default boot entry: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 12:16:43, Info BCD: BcdGetElementDataWithFlags: Failed to open key.Object: {6b5eafc2-954a-11e8-888e-001a7dda7113} Type: 14000008 Status: c0000034
2018-08-01 12:16:43, Info FindOSPartitions: No Recovery sequence found.
2018-08-01 12:16:43, Info FindOSPartitions: Default boot entry locale: en-us
2018-08-01 12:16:43, Info Bitlocker protection for C:\ is either off or suspended.
2018-08-01 12:16:43, Info Unique ID recap for volumes:
2018-08-01 12:16:43, Info Volume name: \\?\Volume{b4a23283-0000-0000-0000-100000000000}
2018-08-01 12:16:43, Info Unique ID size: 12
2018-08-01 12:16:43, Info MBR2GPT: System partition cannot be removed in full OS mode, leaving it untouched.
2018-08-01 12:16:43, Info MBR2GPT: Trying to shrink the OS partition

 

I have a SanDisk SSD

I noticed that when I try to shrink Volume via Disk management it just hangs on the next window, the Activity Monitor shows a Service Host: Disk Defragmenter / Optimize drives process tat is using 10% CPU, has a growing memory usage as well as about 10MB/s disk usage

 

The exact same thing happens when the MBR2GPT process is "stuck" on Trying to shrink the OS partition
I partitioned the disk using a 3rd party software and create a 2GB Unallocated sector and tried again, same issue.

I also remove the 2 recovery partition on the drive. (I have a USB disk with the windows recovery system)
I am not sure what is going on, but I would really hate to do a complete wipe of the drive and start from scratch.

I welcome any ideas at this point.

Mike Terrill's avatar
Mike Terrill
MVP
Aug 02, 2018

Do you have the same problem when running MBR2GPT from WinPE? Chances are, you have something running in the full OS that is causing the issue and this is why it is recommended to run MBR2GPT in WinPE.

  • Alex Chepurnoy's avatar
    Alex Chepurnoy
    Copper Contributor
    Aug 02, 2018

    I was finally able to complete the process.

    I did this through the OS, not in PE.

    The issue is really with how the process went on my SSD.

    It was analyzing it for a while, like a good hour.

    But, before the last time I tried it, when it worked, I used the Defragmenter tool to "optimize" my SSD, then it did the same thing, but now it worked. I can post the logs if it is going to help anyone.

    I did have a boot problem, my BCD was effed up.

    For this I did you WinPE and had to do the assign a letter to the EFI partition, then do the bcdboot c:\windows /s e: command to get the BCD stuff from the installed windows to the EFI partition, now it boots and switched the GPT so all is well.

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