upgrade to 11

A PC showing Legacy can still become eligible for Windows 11 if its firmware supports UEFI: back up the PC, convert the Windows system disk from MBR to GPT, and only then change the firmware from Legacy/CSM to UEFI.

1. Confirm that conversion applies

1. Press Windows key + R, enter msinfo32, and press Enter.
2. In System Summary, confirm BIOS Mode says Legacy.
3. Open Disk Management, right-click the disk containing Windows—not the C: partition—and select Properties > Volumes.
4. Check Partition style:
   • Master Boot Record (MBR): continue with the conversion below.
   • GUID Partition Table (GPT): do not run MBR2GPT; proceed to the firmware change.

Windows 11 requires UEFI firmware with Secure Boot capability, TPM 2.0, and a supported processor, in addition to its memory and storage requirements.^1^

2. Back up and validate the system disk

Back up important files first. If BitLocker/device encryption is enabled, save the recovery key and suspend protection before conversion. Do not continue unless the manufacturer confirms that the computer supports UEFI.

Open Command Prompt as administrator, then validate the current Windows system disk:

mbr2gpt.exe /validate /allowFullOS

Expected result:

Validation completed successfully

MBR2GPT checks the disk layout before changing anything. If validation fails, do not run the conversion command; the disk does not currently satisfy the tool’s layout prerequisites.^2^

3. Convert MBR to GPT

After successful validation, run:

mbr2gpt.exe /convert /allowFullOS

Wait for:

Conversion completed successfully

The tool converts the system disk without deleting its data, creates an EFI System Partition where necessary, installs UEFI boot files, and updates the boot configuration. Afterward, the disk can boot only after the firmware is changed to UEFI.^2^

Do not restart normally into Legacy mode after a successful conversion. Enter the firmware setup and make the corresponding UEFI change.

4. Change the firmware to UEFI

Use the firmware-entry method supplied by the PC or motherboard manufacturer. Where UEFI Firmware Settings is available in Windows:

1. Open Settings > System > Recovery.
2. Under Advanced startup, select Restart now.
3. Select Troubleshoot > Advanced options > UEFI Firmware Settings > Restart.
4. In the firmware settings:
   • Change Boot Mode from Legacy/CSM to UEFI.
   • Make UEFI the only or first boot option.
   • Select Windows Boot Manager as the boot target if shown.
   • Enable Secure Boot if supported.
   • Enable TPM 2.0, which may be named Intel PTT, AMD fTPM, or Security Device.
5. Save the settings and restart.

Microsoft documents that changing from Legacy/CSM to UEFI is necessary for Secure Boot capability; exact menu names vary by manufacturer.^3^

5. Check the result

After Windows starts:

1. Run msinfo32 again.
2. Confirm:
   • BIOS Mode: UEFI
   • Secure Boot State: On, where supported
3. Run tpm.msc and confirm Specification Version: 2.0.
4. Run PC Health Check again.

If Windows does not boot, return to firmware setup and confirm that UEFI/Windows Boot Manager is selected rather than Legacy/CSM.

If the motherboard has no UEFI option, TPM is below version 2.0, or the processor is unsupported, changing the disk layout alone will not make the PC officially eligible for Windows 11.^1^

References

1. Windows 11 System Requirements | Microsoft Support
2. MBR2GPT.EXE
3. Windows 11 and Secure Boot | Microsoft Support