Convert Windows from MBR to GPT

This guide will walk you through preparing your existing Windows 10 system for a Windows 11 upgrade by:

• Converting your system disk from MBR to GPT

• Enabling UEFI and Secure Boot in your firmware settings (BIOS/UEFI)

⚠️ Warning: This process can render your system unbootable if not followed correctly. Back up all important data before proceeding.

Step 1: Check System Compatibility

1. Check BIOS Mode

• Press Windows + R, type msinfo32, and hit Enter.

• Look for “BIOS Mode”:

  • If it says “Legacy”, your system is not using UEFI.

  • If it says “UEFI”, Secure Boot can potentially be enabled directly.

2. Check Partition Style

• Open Disk Management (diskmgmt.msc)

• Right-click on Disk 0 → Properties → Volumes

• Check the Partition style:

  • If it says MBR, conversion is required.

Step 2: Prepare for Conversion

Important: Delete the Recovery Partition (if needed)

The mbr2gpt tool supports only up to 3 primary partitions. If your system has 4 (e.g. a Recovery Partition), conversion will fail.

To delete the recovery partition:

1. Open Disk Management (diskmgmt.msc)

2. Locate the Recovery Partition (usually 500–1000 MB, labeled “Healthy (Recovery Partition)”)

3. Right-click on the recovery partition → Delete Volume

⚠️ Make sure you are deleting the correct partition. This will remove Windows Recovery (WinRE), which can be re-enabled later.

Step 3: Validate with MBR2GPT Tool

1. Open Command Prompt as Administrator

• Right-click the Start menu → "Command Prompt (Admin)" or "Windows PowerShell (Admin)"

2. Run validation

mbr2gpt /validate /allowFullOS

If you see: Validation completed successfully → you’re ready to convert.

Step 4: Convert MBR to GPT

mbr2gpt /convert /allowFullOS

The tool will:

• Create an EFI system partition (ESP)

• Install UEFI boot files

• Convert the disk from MBR to GPT

• Update the boot configuration

Successful output will include: MBR2GPT: Conversion completed successfully

💡 Note: You may see Failed to update ReAgent.xml This is related to Windows Recovery (WinRE) and is not critical. You can fix it later by disabling and re-enabling WinRE.

Step 5: Configure BIOS/UEFI

After the conversion, your system must boot in UEFI mode:

1. Restart your PC and enter BIOS/UEFI setup (Usually by pressing Del, F2, ESC, or F10 during boot)

2. Apply the following settings:

   • Boot Mode / Boot Configuration: UEFI

   • CSM (Legacy Boot): Disabled

   • Secure Boot: Enabled (recommended for Windows 11)

3. Check boot order:

   • Make sure your system drive appears under “UEFI: [Drive Name]” and is at the top of the list.

4. Save and exit BIOS

Step 6: Confirm UEFI & Secure Boot

After Windows boots:

1. Press Windows + R → type msinfo32 → Enter

2. Check:

   • BIOS Mode: should be UEFI

   • Secure Boot State: should be On

If both are correct, your system is now fully ready for Windows 11.

Step 7: Upgrade to Windows 11

You can now proceed with the Windows 11 upgrade using:

• The Windows 11 Installation Assistant

• A bootable USB stick

• Or the official ISO file