How to upgrade to windows 11 from Windows 10 by keeping files and apps?

Though ThinkCentre M900 was one of the most powerful business desktop when it was released in 2015, it is not officially supported by Windows 11 as the CPU is not eligible to run Windows 11. I guess TPM 2.0 is also not available. This means you can't upgrade this PC to Windows 11 from Windows 10 Pro in usual ways, such as from Windows update center or using Windows 11 installation assistant app.

Based on this official document, at least i7-8086K is required:

https://learn.microsoft.com/en-us/windows-hardware/design/minimum/supported/windows-11-supported-intel-processors

How to upgrade to Windows 11 from Windows 10

Step 1: Back Up Your Data

Use File History or an external drive to back up important files.

Step 2: Modify Registry to Bypass Checks

Press Win + R, type regedit, and hit Enter. Navigate to:

HKEY_LOCAL_MACHINE\SYSTEM\Setup\MoSetup

Right-click → New → DWORD (32-bit) Value → Name it:

AllowUpgradesWithUnsupportedTPMOrCPU

Double-click it and set Value data to 1. Close Registry Editor and restart.

Step 3: Start Upgrading to Windows 11 from Windows 10.

Download Windows 11 ISO from Microsoft. Double click the file to mount it. Now, go to the root folder and run the setup program to upgrade Windows 10 to Windows 11 by keeping files, apps and settings.