Cannot find os partition s for disk 0 как исправить

Best Way to Fix “MBR2GPT Cannot Find OS Partition” in Windows 10

Generally, you can convert boot disk from MBR to GPT via the MBR2GPT.exe tool. However, sometimes, you might meet the “MBR2GPT cannot find OS partition” error message. Don’t worry, here we list the workable solution.

By Emily / Last Updated May 12, 2023

• MBR2GPT Cannot find OS Partition for Disk 0?
• Why MBR2GPT cannot find OS partiiton and how to solve it?
• Best way to evade “MBR2GPT cannot find OS partition” issue
• Summary

MBR2GPT Cannot find OS Partition for Disk 0?

Hi, experts, when i trying to convert my Win10 boot disk from MBR to GPT partition table, it keeps failing with the «Cannot find OS Partition(s) for disk 0». I have read many articles but nobody offered a clear solution for this. Anyone can help me out? Thanks a lot!

MBR2GPT.EXE is a tool to help users convert an operating system disk from the MBR to GPT partition style without modifying or deleting any data on the boot disk. You can run it from a Windows Preinstallation Environment (Windows PE) command prompt, or from the full Windows 10 operating system (OS) by using the /allowFullOS option. It is available and located in the Windows\System32 directory on a computer running Windows 10 version 1703 or later.

To convert a system disk with earlier versions of Windows such as Windows 7, 8, or 8.1, you have to upgrade the operating system to Windows 10 first, then perform the MBR to GPT conversion. In particular, Microsoft declared that Windows 11 requires supporting UEFI if users plan to upgrade their Windows 10 to Windows 11 through the «Check for Update» feature. Thus, converting their MBR disk to GPT is also necessary.

Why MBR2GPT cannot find OS partition for disk 0 and how to solve it?

In general, you can use the MBR2GPT command line tool to convert your system disk from MBR to GPT. After this is done, you can boot Windows in modern UEFI mode rather than the old BIOS Legacy mode, and you can make the fullest use of 2TB+ hard drive. However, sometimes, it does not work and prompts the error message saying «Cannot find OS partition for disk 0». There could be many reasons behind this MBR2GPT conversion failure. One of the most important reasons might be the bad entries in the Boot Configuration data. To solve it, you can refer to the subsequent steps:

Step 1. Make use of diskpart and run the following commands to find out the OS partition and the system reserved partition and assign them a drive letter.

▸diskpart

▸select disk 0: the operating system disk

▸list partition

▸select partition 2: the partition where the Windows OS is installed

▸assign drive letter= w (or other available drive letter)

▸select partition 1: the system reserved partition

▸assign drive letter= b (or other available drive letter)

▸exit: exit the diskpart.exe

Step 2. Run the command “X: \Sources>dir /a w: \ “to take a further look into the Windows system partition to check whether there are the boot folder inside. If there is not required boot folders, then run the command “X: \Sources>dir /a b: \” to check the system reserved partition.

Step 3. After you find the boot folder in either system partition or system reserved partition, you need to run the “X: \Sources>dir /a b: \Boot” to invoke the bcdedit tool and point it to the boot configuration data store that you have found.

Step 4. Look out the invalid entries now. Run the command: “X: \Sources>bcdedit /store B:\boot\bcd /enum all”. There are many hints for bad or invalid entries. For example, you might find “unknown” in some entry. They can be the remnant of a previous Windows installation or caused by some vicious software.

Step 5. Copy the identifier of the bad entry. Then, point bcdedit to the store again and ask it to delete the bad entry using the copied identifier.

Step 6. Then you can try to run the “X: \Sources>bcdedit /store B:\boot\bcd /enum all” command again to check whether all are OK now.

When everything goes well, try the MBR2GPT tool again. You can make it done successfully this time.

Best way to evade «MBR2GPT cannot find OS partition» issue

Refer to the above solution and you can solve the “cannot find os partitions for disk 0” in MBR2GPT.exe tool. However, it is too complicatd and difficult to follow for most users. So, here we would like to share an easier tool to help you finish the MBR and GPT conversion. That is AOMEI Partition Assistant Professional. Compared with MBR2GPT, it owns the following advantages:

Finish the MBR to GPT conversion on an intuitive interface, easy to follow for both experts and newbies; Be able to work well on all editions of Windows 11/10/8/7 and Windows XP/Vista (32-bit and 64-bit); Support converting both system disk and non-system disk to from MBR to GPT partition styles without deleting any data on the disk. Besides converting disk from MBR to GPT, it can also convert any disk from GPT to MBR, likewise, without modifying disk data.

Now, you can download its demo version for a free trial or simulation.

Secure Download

Notes:✎. After the boot disk has been converted to GPT partition style, the firmware must be reconfigured from Legacy BIOS to UEFI. Make sure that your device supports UEFI before attempting to convert the system disk.

Step 1. Install and run AOMEI Partition Assistant Professional. Right-click the system disk and choose “Convert to GPT” or click the disk and choose «Convert to GPT» from the right column.

Step 2. In the next window, click “OK” to confirm your operation.

Step 3. Back to the main interface, click on “Apply” to commit the pending operation.

If you want to convert MBR or GPT without loading operating system, you can first use this software to create a bootabale media, then boot computer from it and finish the conversion.

Summary

This page tells how to solve “MBR2GPT cannot find OS partition” on Windows 10. Besides, we also introduce another tool to help you easily get around such issues. The AOMEI Partition Assistant Professional also comes with many other functions: clone MBR disk to GPT disk, or GPT disk to MBR disk, clone partition, transfer OS between MBR and GPT disk, convert dynamic disk to basic disk without deleting volumes, and more. If you are running Windows Server, please switch to the Server edition.

Free Partition Manager

• Resize and Move Partition
• System/Disk Clone
• Convert MBR/GPT Disk
• Check & Fix Disk Errors

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One way to fix MBR2GPT “Cannot find OS partition”

In Windows 10 1703 update, Microsoft added MBR2GPT command line tool, that lets you convert your system disk’s partition table from MBR to GPT. In general, this is done, so that Windows can boot in modern UEFI mode instead of old BIOS mode and to support disks bigger than 2 TB. Unfortunately, it didn’t work for me as I always got “Cannot find OS partition” error.

C:\Windows\system32>MBR2GPT.EXE /convert /allowfullos

MBR2GPT will now attempt to convert the default book disk.
If conversion is successful the disk can only be booted in GPT mode.
These changes cannot be undone!

MBR2GPT: Attempting to convert disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Cannot find OS partition(s) for disk 0

After checking logs (%windir%/setupact.log), it was clear it had a problem with my recovery boot option — it was going through all GUIDs in my BCD (Boot Configuration Data), and failed on the one assigned to recovery entry. This entry was disabled (yet still had GUID assigned to it, which apparently led nowhere and that seems to have been the root cause). I searched some discussion forums, and most of them said that I would have to somehow create recovery partition.

C:\WINDOWS\system32>reagentc /info
Windows Recovery Environment (Windows RE) and system reset configurationInformation:
Windows RE status: Disabled
Windows RE location: Boot Configuration Data (BCD) identifier: 9c010806–7e29–11e8–86cb-001a7dda710c Recovery image location:
Recovery image index: 0
Custom image location:
Custom image index: 0REAGENTC.EXE: Operation Successful. 

Fortunately, it turned out to be a lot easier 🙂 Windows has another command line tool, called REAgentC, which can be used to manage its recovery environment. I ran reagentc /info, which showed that recovery is disabled and its location is not set, but it had assigned the same GUID that was failing when running MBR2GPT. So, I ran reagentc /enable, which set recovery location and voila, this time MBR2GPT finished its job successfully.

All commands mentioned here should be run from elevated command prompt (right click on cmd.exe and choose “Run as administrator”).

Fix MBR2GPT failed errors and issues on Windows 11/10

The MBR2GPT.exe is a Windows 11/10 native disk conversion tool PC users can use to convert a disk with the MBR partition table to a GPT without data loss and without the need to delete the existing partition. In this post, we will explore the various instances of the MBR2GPT failed errors message, each with its unique description, as well as provide the most suitable solutions as it relates to each of the instances.

Why is MBR2GPT not working?

The MBR2GPT tool will work only if your system meets the minimum requirements for the tool. Some of these requirements include Windows 10 version 1703 or later, your PC should have 64-bit architecture, Bitlocker encryption should be disabled on your disk, the disk should be currently in MBR and should have enough space not occupied by partitions to store the primary and secondary GPTs (16KB + 2 sectors at the front of the disk and 16KB + 1 sector at the end of the disk), etc.

Fix MBR2GPT failed errors on Windows 11/10

• MBR2GPT disk layout validation failed
• MBR2GPT cannot find OS partition
• MBR2GPT cannot find room for the EFI system partition
• MBR2GPT non system disk
• MBR2GPT cannot install new boot files

See the sections below in line with the exact error information on your computer to view solutions.

MBR2GPT disk layout validation failed

You’ll encounter this error because MBR2GPT program only applies to Windows 10 version 1703, Windows 11 or later. So, if you’re running the tool on Windows 10 version earlier than v1703, this MBR2GPT disk layout validation failed error will occur.

• If you are using a computer running Windows 7, 8, or 8.1, you can upgrade to a currently supported version/build of Windows 11/10.
• If you have installed earlier versions of Windows 10 such as versions 1507, 1511, and 1607, you must run the tool while booting into later versions of Windows 10 or Windows 11 and perform an offline conversion.
• If the MBR disk has 4 partitions the conversion will fail and you’ll receive this error. In this case, try deleting one partition and see if that helps.

MBR2GPT cannot find OS partition

There are a couple of reasons for this error; one of the most common is bad entries in the Boot Configuration Data (BCD). You may also encounter this error if Windows RE (Recovery Environment) is disabled and its location is not set, but it had assigned the same GUID that was failing when running MBR2GPT.

Solutions

• Rebuild BCD file and run MBR2GPT.exe again.
• Enable Windows RE.

MBR2GPT cannot find room for the EFI system partition

• More than four hard drive partitions.
• Hard disk with multiple bad sectors.
• Shrinking or defragmentation failure due to system files, locked files.
• Insufficient space for System Reserved partition.

• Check if the disk is encrypted. If it is, unlock it.
• Before conversion, you should check if Windows 10 version is 1703 or higher. To check, click Start, type winver, and hit Enter. You’ll receive an output stating your current version/build of Windows 10.
• Although MBR2GPT can run in full OS we strongly suggest running it in WinPE. Since MBR2GPT is a low-level operation there are many things that can interfere with the conversion. WinPE is relatively clean and doesn’t have a lot of the things that may cause issues, like certain types of filter drivers that touch the disk. However, if you can’t run MBR2GPT in WinPE, then you may need to consider disabling the Page file, Hiberfile, and then rerun MBR2GPT.exe.
• Open Disk Management and shrink C drive to about 2GB and leave it unallocated. If that fails, then that means your C drive is fragmented. In which case, you can defrag the disk and shrink it again. Once done, try MBR2GPT. If it fails again, you can use EaseUS Partition Manager to resize the system partition to 600 MBs and then extend the System Reserved partition/volume.

You cannot use MBR2GPT to convert data (non-system) disk from MBR to GPT. If you do want to convert a data disk, you can convert MBR to GPT in Windows 11/10 via Disk Management or Command Prompt – keep in mind, you are at risk of data loss because you have to delete all partitions or volumes on the disk before conversion.

MBR2GPT cannot install new boot files

As already pointed out, it’s not possible to convert disks with older versions of Windows OS, such as Windows 8.x and Windows 7, but you can upgrade to Windows 11/10, and then use the tool to convert from MBR to GPT.

How do I use MBR2GPT in Windows 10?

If you want to upgrade to Windows 11, your hard disk should have a GPT disk partition style. If not, you can convert it to GPT but this process involves data loss. But the MBR2GPT tool lets you convert MBR to GPT without data loss. This tool is located in the System32 folder and you can launch it from Windows PE (Windows Preinstallation Environment) command prompt, as well as from the Windows 10 OS.

Let’s know in the comments section below any other MBR2GPT failed errors that you might have encountered that none of the solutions outlined in this post didn’t resolve the issue.

MBR2GPT failing with «Cannot find OS partition(s) for disk 0»

I’m trying to use MBR2GPT to convert an MBR/BIOS disk to GPT/UEFI. I’m getting the error Cannot find OS partition(s) for disk 0 . I found this in setupact.log :

GetOSDeviceVolume: Cannot get NT path for entry.[gle=0x000000ea] FindOSPartitions: Cannot get volume name for the recovery boot entry. Error: 0x000000EA[gle=0x000000ea] Cannot find OS partition(s) for disk 0[gle=0x000000ea] 

My OS is a recent Windows 10 version. It might be a Windows 7 upgrade, and the disk has been resized in the past with gparted . This is in a VM with a snapshot, so I can run risky commands and revert without any problems. Command I’m running:

C:\WINDOWS\system32>MBR2GPT.EXE /convert /allowfullos MBR2GPT will now attempt to convert the default book disk. If conversion is successful the disk can only be booted in GPT mode. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes Cannot find OS partition(s) for disk 0 

Complete setupact.log :

2021-09-28 10:10:50, Info MBR2GPT was explicitly asked to run in full OS mode. 2021-09-28 10:10:50, Info MBR2GPT: System disk number is 0 2021-09-28 10:10:50, Info MBR2GPT: Attempting to convert disk 0 2021-09-28 10:10:50, Info MBR2GPT: Retrieving layout of disk 2021-09-28 10:10:50, Info MBR2GPT: Initial partition information 2021-09-28 10:10:50, Info =========================================================== 2021-09-28 10:10:50, Info Partition layout for disk: 0 2021-09-28 10:10:50, Info Partition style : MBR 2021-09-28 10:10:50, Info MBR signature: 53033256 2021-09-28 10:10:50, Info Number of partitions : 3 2021-09-28 10:10:50, Info ===================PARTITION=============================== 2021-09-28 10:10:50, Info Number: 1 2021-09-28 10:10:50, Info Type: 7 2021-09-28 10:10:50, Info Boot: Yes 2021-09-28 10:10:50, Info Recognized: Yes 2021-09-28 10:10:50, Info Style: 0 2021-09-28 10:10:50, Info Offset: 1048576 2021-09-28 10:10:50, Info Length: 524288000 2021-09-28 10:10:50, Info Volume: \\?\Volume\ 2021-09-28 10:10:50, Info Drive: None 2021-09-28 10:10:50, Info NT Path: \Device\HardDisk0\Partition1 2021-09-28 10:10:50, Info ===================PARTITION=============================== 2021-09-28 10:10:50, Info Number: 2 2021-09-28 10:10:50, Info Type: 7 2021-09-28 10:10:50, Info Boot: No 2021-09-28 10:10:50, Info Recognized: Yes 2021-09-28 10:10:50, Info Style: 0 2021-09-28 10:10:50, Info Offset: 525336576 2021-09-28 10:10:50, Info Length: 79455782912 2021-09-28 10:10:50, Info Volume: \\?\Volume\ 2021-09-28 10:10:50, Info Drive: C:\ 2021-09-28 10:10:50, Info NT Path: \Device\HardDisk0\Partition2 2021-09-28 10:10:50, Info ===================PARTITION=============================== 2021-09-28 10:10:50, Info Number: 3 2021-09-28 10:10:50, Info Type: 39 2021-09-28 10:10:50, Info Boot: No 2021-09-28 10:10:50, Info Recognized: Yes 2021-09-28 10:10:50, Info Style: 0 2021-09-28 10:10:50, Info Offset: 79982622720 2021-09-28 10:10:50, Info Length: 542868480 2021-09-28 10:10:50, Info Volume: \\?\Volume\ 2021-09-28 10:10:50, Info Drive: None 2021-09-28 10:10:50, Info NT Path: \Device\HardDisk0\Partition3 2021-09-28 10:10:50, Info =========================================================== 2021-09-28 10:10:50, Info ESP partition size will be 104857600 2021-09-28 10:10:50, Info MBR2GPT: Validating layout, disk sector size is: 512 bytes 2021-09-28 10:10:50, Info BCD: Opening store. Flags: 0x0 2021-09-28 10:10:50, Info BCD: Store path: "\??\GLOBALROOT\device\harddisk0\partition1\Boot\BCD" 2021-09-28 10:10:50, Info BCD: Loaded hive at BCD00000000 2021-09-28 10:10:50, Info BCD: Opening object 2021-09-28 10:10:50, Info FindOSPartitions: Default boot entry: 2021-09-28 10:10:50, Info BCD: Opening object 2021-09-28 10:10:50, Info VERBOSE: Device path: \Device\HarddiskVolume2 2021-09-28 10:10:50, Info VERBOSE: Dos path: \\?\GLOBALROOT\Device\HarddiskVolume2 2021-09-28 10:10:50, Info FindOSPartitions: Volume name for the default boot entry: \\?\Volume\ 2021-09-28 10:10:50, Info BCD: Opening object 2021-09-28 10:10:50, Error GetOSDeviceVolume: Cannot get NT path for entry.[gle=0x000000ea] 2021-09-28 10:10:50, Error FindOSPartitions: Cannot get volume name for the recovery boot entry. Error: 0x000000EA[gle=0x000000ea] 2021-09-28 10:10:50, Error Cannot find OS partition(s) for disk 0[gle=0x000000ea] 2021-09-28 10:10:50, Info MBR2GPT: Partition information at error point 2021-09-28 10:10:50, Info =========================================================== 2021-09-28 10:10:50, Info Partition layout for disk: 0 2021-09-28 10:10:50, Info Partition style : MBR 2021-09-28 10:10:50, Info MBR signature: 53033256 2021-09-28 10:10:50, Info Number of partitions : 3 2021-09-28 10:10:50, Info ===================PARTITION=============================== 2021-09-28 10:10:50, Info Number: 1 2021-09-28 10:10:50, Info Type: 7 2021-09-28 10:10:50, Info Boot: Yes 2021-09-28 10:10:50, Info Recognized: Yes 2021-09-28 10:10:50, Info Style: 0 2021-09-28 10:10:50, Info Offset: 1048576 2021-09-28 10:10:50, Info Length: 524288000 2021-09-28 10:10:50, Info Volume: \\?\Volume\ 2021-09-28 10:10:50, Info Drive: None 2021-09-28 10:10:50, Info NT Path: \Device\HardDisk0\Partition1 2021-09-28 10:10:50, Info ===================PARTITION=============================== 2021-09-28 10:10:50, Info Number: 2 2021-09-28 10:10:50, Info Type: 7 2021-09-28 10:10:50, Info Boot: No 2021-09-28 10:10:50, Info Recognized: Yes 2021-09-28 10:10:50, Info Style: 0 2021-09-28 10:10:50, Info Offset: 525336576 2021-09-28 10:10:50, Info Length: 79455782912 2021-09-28 10:10:50, Info Volume: \\?\Volume\ 2021-09-28 10:10:50, Info Drive: C:\ 2021-09-28 10:10:50, Info NT Path: \Device\HardDisk0\Partition2 2021-09-28 10:10:50, Info ===================PARTITION=============================== 2021-09-28 10:10:50, Info Number: 3 2021-09-28 10:10:50, Info Type: 39 2021-09-28 10:10:50, Info Boot: No 2021-09-28 10:10:50, Info Recognized: Yes 2021-09-28 10:10:50, Info Style: 0 2021-09-28 10:10:50, Info Offset: 79982622720 2021-09-28 10:10:50, Info Length: 542868480 2021-09-28 10:10:50, Info Volume: \\?\Volume\ 2021-09-28 10:10:50, Info Drive: None 2021-09-28 10:10:50, Info NT Path: \Device\HardDisk0\Partition3 2021-09-28 10:10:50, Info =========================================================== 

C:\WINDOWS\system32>bcdedit Windows Boot Manager -------------------- identifier device partition=\Device\HarddiskVolume1 description Windows Boot Manager locale en-US inherit default resumeobject displayorder toolsdisplayorder timeout 30 Windows Boot Loader ------------------- identifier device partition=C: path \WINDOWS\system32\winload.exe description Windows 10 locale en-US inherit recoverysequence displaymessageoverride Recovery recoveryenabled Yes allowedinmemorysettings 0x15000075 osdevice partition=C: systemroot \WINDOWS resumeobject nx OptIn bootmenupolicy Standard