Good morning everyone!

Here we are again, with a new problem, and obviously a new solution: the upgrade from Windows 10 to Windows 11.

About time, you might say! But a tiny clarification is needed here: as an IT technician, one of the things that has always bored me is spending my free time fixing my own devices. Because of this, my devices are always the last ones to be put on the waiting list.

Better late than never. At this point, however, you might wonder what's so special about this how-to compared to the hundreds available on the internet, especially for a procedure that requires no dark magic. Well, in my case, as Murphy's Law dictates, things got a bit more complicated. I had originally set up an MBR partition instead of GPT, a problem compounded by the fact that I hadn't enabled the BIOS in UEFI mode nor enabled Secure Boot.

In short, I unconsciously complicated things just to make the solution more interesting. Let's proceed and see how we managed to get out of this IT mess.

Phase 1: The illusions of the Microsoft tool (MBR2GPT)

On paper, Microsoft provides us with a command-line tool that should do the magic: MBR2GPT. The idea is that, by running it with administrator privileges, it converts the disk from MBR to GPT without touching the data, creating a ready-to-use EFI partition.

Let's verify that the partitions are ready using the Microsoft tool:

mbr2gpt /validate /disk:0 /allowFullOS

If the validation is successful, we execute the command. Unfortunately for me, the validation failed, and I had to rebuild the bootloader manually. Once the bootloader was rebuilt, I moved on to the actual conversion:

mbr2gpt /convert /disk:0 /allowFullOS

WARNING: TO CONVERT PARTITIONS WITH BITLOCKER, IT IS NECESSARY TO SUSPEND OR DISABLE BITLOCKER FIRST, OTHERWISE YOU WON'T BE ABLE TO REBOOT THE PC.

The tool creates the EFI and MSR partitions and updates the BCD without formatting. Do not unplug the PC during the operation.

At this point, we need to restart the PC in UEFI mode. Let's proceed from Windows:
Settings → System → Recovery → Advanced startup → Restart now → Troubleshoot → Advanced options → UEFI Firmware Settings → Restart.

Upon reboot, we will have to enter the BIOS by pressing a key between F11 or F12 (depending on your PC manufacturer) before Windows boots. Once inside the BIOS, we will disable Legacy/CSM and set the boot mode strictly to UEFI. Save the settings and exit.

(Editor's note: If you have to use Diskpart to force a partition deletion like I did because of corrupt EFI volumes left behind, you might run into this beautiful Windows safety block: Virtual Disk Service error: Delete is not allowed on the current boot, system, pagefile, crashdump or hibernation volume. Just use the override parameter to bypass it. And when fixing the bootloader with bcdboot, wait for the majestic Boot files successfully created.)

At this point, Windows will boot up, and we can proceed with the upgrade to Windows 11 by going to the Windows Update tab and clicking to check for updates. If this doesn't show the option to switch to Windows 11, the reason you are not seeing the update yet is simply a matter of server timing. Microsoft handles the transition to Windows 11 with a staged rollout. Even if your PC is ready today, the Windows Update algorithm might put you in a "queue" and show you the banner weeks or even months from now. Obviously, there is no reason to wait for Microsoft's server timelines. There is an official and direct method to trigger the update immediately, keeping all your programs, files, and settings intact.

Here is how to force a clean upgrade:

The Windows 11 Installation Assistant

This is the official Microsoft tool designed specifically for those who have a compatible PC but don't want to wait for the Windows Update notification.

1. Go to the official Microsoft download page by googling "Download Windows 11" (make sure the site is microsoft.com).
2. The first option at the top will be the Windows 11 Installation Assistant.
3. Click on Download Now.
4. Run the downloaded file (Windows11InstallationAssistant.exe). Note: it might ask you to download and install the "PC Health Check" app for a final double-check; do it if prompted.
5. Accept the license terms and click on Accept and install.

Note: If you run into TPM issues right after switching from Legacy to UEFI, you might see errors in Windows Security like Device health attestation isn't supported on this device and TPM storage is not available. Please clear your TPM. Simply click on Clear TPM in the UI and confirm upon reboot to reset the cryptographic keys.

At this point, the Assistant will do everything on its own. It will start the background download of Windows 11 (you can continue using the PC in the meantime), prepare the files, and, when ready, will ask you to restart. The reboot will take some time, similar to a large cumulative update, and upon completion, you will find yourself directly on the new Windows 11 desktop.