The error: MBR2GPT validation failed
MBR2GPT is a tool designed by Microsoft to help people convert a disk from the Master
Boot Record (MBR) to the GUID Partition Table (GPT) partition style without
modifying or deleting data on the disk. It’s very useful when you own a hard
drive larger than 2TB and want to make full use of it. It’s also needed when you
plan to create more than 4 primary partitions.
Despite the convenience MBR2GPT
utility brings us, some people are disappointed by MBR2GPT errors. Here is a user
sharing the experience of encountering MBR2GPT validation failed problem:
“I am using a 4TB HDD as a storage drive on my pc, with a 500GB SSD for the OS
and other programs. I am only able to partition 2TB of my HHD due to it having a MBR
partition style, and would like to convert it to GPT so I can use all of its
available space. The 2TB partition is almost full, and only has 67GB remaining,
which is why I am trying to convert it.
After using the command 'mbr2gpt /validate /disk:1 /allowFullOS' , I get the
message 'Disk layout validation failed for disk 1'. How can I fix this?”
To solve the problem, we may figure out the causes first.
How comes MBR2GPT validation failed?
Here I'm going to show you two possible causes for MBR2GPT validation failed and corresponding solutions:
Inapplicable Windows system
MBR2GPT program only applies to Windows 10 version 1703 (also known as the Creator's
Update) or later. Inapplicable Windows system can lead to MBR2GPT disk layout
failed.
lf you are using a computer running Windows 7, 8, or 8.1, please upgrade the
operating system to Windows 10.
lf you have installed earlier versions of Windows 10 such as versions
1507, 1511, and 1607, you must run the tool while booted into Windows 10 version
1703 or later and perform an offline conversion.
Non-system disk
MBR2GPT is a tool to convert any attached MBR-formatted system disk to the GPT
partition format. You cannot use it to convert non-system disks from MBR to GPT. If
you do want to convert a data disk, you can convert MBR to GPT
in Windows 10 via Disk Management or Command Prompt. However, you are at a
risk of losing data because you have to delete all partitions or volumes on the disk
before conversion.
Quick Fix to MBR2GPT Validation Failed
When you meet MBR2GPT
conversion failed caused by invalidation, you must be thinking whether there is
an alternative to MBR2GPT. Certainly there is! AOMEI Partition Assistant
Professional can help you convert MBR to GPT without data loss quickly
and safely.
What’s more, it overcomes MBR2GPT’s shortcomings—it applies to all Windows 10
versions as well as Windows 7, 8/8.1, XP and Vista; it can not only convert a system
disk from MBR to GPT but also a storage disk. I’ll show you how to fix MBR2GPT
validation failed quickly via AOMEI Partition Assistant in detail:
Step 1. Install and launch AOMEI Partition Assistant. Right click
the disk you want to convert and select “Convert to GPT Disk”.

Step 2. Click “OK” in the pop-up dialog to confirm the operation. If
you are converting a system disk, you will get a prompt that the GPT disk boots from
UEFI mode.

Step 3. Click “Apply” to commit the operations.

Tips:
For converting a system disk, you must switch the firmware to boot from UEFI
mode after conversion.
To convert MBR to GPT in Windows PE with AOMEI Partition Assistant, please
use “Make Bootable Media” feature to complete the task.
AOMEI Partition Assistant can also convert
GPT to MBR without data loss in reverse.
Summary
To fix MBR2GPT validation failed error, please turn to AOMEI Partition Assistant. You
can also format
external hard drive in RAW, stop
checking file system on C in Windows 7 via AOMEI Partition Assistant. Get
this tool and enjoy all the wonderful functions!