How to Solve the Specified Disk Is Not Convertible Issue

Error: The specified disk is not convertible

"Hello everyone, I need to convert my system disk from MBR to GPT. I prepared a Windows installation USB and booted from it, trying to use the command prompt in Windows PE to convert the system disk, but when I input the "convert mbr to gpt" command, I received an error message: "The specified disk is not convertible." Can anyone tell me why this happens and what is the solution?"

As we know, MBR and GPT are two different partition styles. In most cases, we are using MBR disk. However, with the development of tech, the status of GPT disk has risen. Compared with MBR, GPT has advantages in disk capacity and primary partition numbers. And you should convert MBR to GPT for Windows 11 updates if you upgrade Windows 10 to Windows 11 from "Check for updates". 

Why "the specified disk is not convertible" happens?

When you use the Command Prompt to convert the disk, you may receive: "Virtual Disk Service Error: The specified disk is not convertible". Two main scenarios lead to this error:

1️⃣The Specified Disk Is Not Convertible Because The Size Is Less Than The Minimum Size Required:

This error usually occurs when the user is unable to initialize a disk or convert a disk to GPT using Disk Management. And too many bad sectors on the hard disk and file system corruption can also trigger the error.

2️⃣The Specified Disk Is Not Convertible. CORMs and DVDs Are Examples of Disks That Are Not

The reason for this error is that there are partitions on your hard disk. The Command Prompt supports converting MBR/GPT to MBR/GPT, but one of the most important conditions is that there are no partitions on disk, including system partition.

When "Virtual Disk Service Error Specified disk is not convertible" is triggered, you can try the following methods to eliminate the error.

How to Fix the Specified Disk Is Not Convertible

This section describes a detailed solution on how to resolve Specified Disk Is Not Convertible in Windows 11/10/8/7:

Method 1. Fix "The specified disk is not convertible" without deleting partitions

To solve the error quickly and safely, the best way is to try a professional third-party tool - AOMEI Partition Assistant Professional. It provides the complete guide to fix The specified disk is not convertible error:

• As the best disk management alternative, it automatically recognizes hard disks and easily initializes them to GPT/MBR.
• With an MBR/GPT converter, it can convert the system/data disk when Windows is running, and there is no boot failure problem on the converted disk.
• When there are bad sectors on the hard disk, it provides the Surface Test and Check Partition features to check for bad sectors and repair file system errors on the disk.

More importantly, it can complete all the jobs with a few clicks. Please download the Demo version to see how to convert MBR to GPT and fix the specified disk not convertible.

Step 1. Install and run AOMEI Partition Assistant Professional. Right-click on the disk that shows “virtual disk service error the specified disk is not convertible” error message, and then select the option “Convert to GPT”.

Step 2. Click "OK" to continue.

Step 3. Click “Apply” to begin the conversion.

When the conversion has completed, you need to change Legacy BIOS to UEFI boot mode before you can load Windows. 

In addition, AOMEI Partition Assistant can help you create/extend/resize/format/copy partitions, convert NTFS to FAT, change cluster sizes, migrate operating systems, rebuild MBRs, and more.

Method 2. Clean Partition and Convert Disk via Diskpart

In addition, it can help you create/extend/resize/format/copy partitions, convert NTFS to FAT, change cluster sizes, migrate operating systems, rebuild MBRs, and more. So you must clean the partitions on the hard disk before conversion. To solve this problem, you need to enter the following commands in Diskpart:

● list disk
● select disk 1 (1 is the disk number of the hard drive you want to convert)
● clean (This operation will wipe all data on the selected hard drive, please backup important data before you start.)
● convert gpt

After that, type in "exit" and press Enter twice to exit Diskpart. If you don’t want to clean the disk when converting MBR to GPT or convert system disk to GPT, you can choose AOMEI Partition Assistant Professional to directly convert disk from MBR/GPT to MBR/GPT without losing data.

Warning: You cannot convert the system disk to GPT because Windows does not support deleting the system volume.

Conclusion

If you want to fix "the specified disk is not convertible", AOMEI Partition Assistant must be your first choice. 

In addition to convert between MBR/GPT to MBR/GPT. It can also convert dynamic disk to basic, convert primary partition to logical partition, and more functions are waiting for you to unlock. If you are running Windows Server 2025/2022/2019/2016/2012, 2003, then Server Edition will provide you with the perfect solution for any errors that you may encounter!