How to install 25H2 enablement package?

Windows 11 officially requires TPM 2.0 for installation and support. While it is technically possible to install Windows 11 on systems with only TPM 1.2 by bypassing system checks (using utilities like RUFUS to Disable security requirements and create a bootable Win11 OS image) , this is not recommended, as Microsoft does not guarantee updates or support for such configurations. TPM 2.0 provides necessary, updated security, while TPM 1.2 uses outdated SHA-1 algorithms.

If you want to try, I recommend the following:

1. TPM Support: Some PCs support (both) TPM 1.2 and TPM 2.0! Enter UEFI / BIOS setup, then locate Security / TPM settings and check to see if you can change your TPM from 1.2 to 2.0.
   1. Note: If Yes, then change from TPM 1.2 to TPM 2.0 immediately, save and exit.
2. Firmware Update: If only TPM 1.2 is available then Go To your PC manufacturer's website and locate the latest UEFI FW / BIOS update and upgrade your UEFI / BIOS to the latest version (Do Not attempt to run Windows 11 with down-level FW).
3. Note: After FW Update, Go back to Step 1 above and check if you can now Enable TPM 2.0. If YES, then Enable TPM 2.0 (and/or) proceed to Step 4 below.
4. Secure Boot: If TPM 2.0 is Enabled then Enable Secure Boot
5. Windows 10 Updates: If possible - Upgrade your current Windows 10 from 21H2 > 22H2 > 23H2 > 24H2 (Do Not ignore this if it is possible).
6. Acquire Windows 11 Pro: Locate and purchase / download either your PCs manufacturer's OEM Windows 11 OS image (or) Purchase a generic (non-specific) OEM Windows 11 Pro DVD media
   1. Note: A Retail version should work too but Do Not try to use another OEM manufacturer's OS image media. (best to use Pro and Not Home edition if possible)
7. Backup (full backup): of your current Windows 10 OS and Data
   1. Note: I would purchase another SSD then swap out your current Windows SSD / HDD so it remains intact (after backup is done.)
8. UEFI Mode: If you PC is currently configured for BIOS / Legacy Mode then Go To UEFI / BIOS setup and change the Boot Mode to UEFI
   1. Note: Boot Mode: https://dotnet.territoriali.olinfo.it/en-us/windows-hardware/manufacture/desktop/boot-to-uefi-mode-or-legacy-bios-mode?view=windows-11
9. Deployment Method: If TPM 2.0 is Enabled (see steps 1 & 2 above), then you may use either of the following deployment options:
   1. Note: (If Windows 10 Updates are successful then you may attempt Windows Upgrade) - If Windows 10 Updates were Not possible, then only attempt a clean / new OS installation (will wipe all existing data).
      1. DVD media install: Configure PC to boot from internal DVD drive or external USB DVD drive. Insert DVD media and boot from DVD and perform Win11 Upgrade / Clean install as appropriate.
      2. Rufus Bootable Flash Drive: If only TPM 1.2 is available then you will need to create a RUFUS Bootable Flash Drive with Windows 11 security (pre-requisites) Disabled.
10. Create Rufus Media: (best method) Go to https://rufus.ie/en/ and download the latest Portable version.
    1. Place Win11 DVD media (if purchased) in the DVD drive (or) if Win11 is an .ISO image then copy to a local folder on the system you are creating the Rufus media on.
    2. Insert USB flash drive into PC
    3. Run Rufus as an Administrator
    4. Confirm Rufus has selected the correct USB flash drive!
    5. Within Rufus app, point Rufus to the location of the Win11 DVD / .ISO media
    6. Disable Win11 Security pre-requisites ONLY IF YOUR PC DOES NOT SUPPORT TPM 2.0.!!!
    7. If Only TPM 1.2 is possible then be sure to Disable 'Remove requirement for 4GB+RAM, Secure Boot and TPM as shown below.
    8. Refer to documentation / examples here: https://rufus.ie/en/
    9. Leave other Rufus settings at default and Click OK
    10. Click Start
    11. When Status (Ready) progress bar is 100% Green, then close the Rufus utility.
    12. Done with Rufus.
11. Insert Rufus Bootable flash drive: media into PC to install Windows 11
12. Double-confirm Boot Device: of the PC is set to boot from USB flash driver as the primary boot device (and/or) Press F12 to boot from "one-time" boot device (and/or) Go To UEFI setup and select the USB flash driver as a one-time boot device.
13. Boot PC from Rufus flash drive: Press any key (ie space bar) when prompted to boot the Windows 11 installation media
14. Follow the on-screen prompts: to Upgrade (if possible) but Clean OS installation is recommended
15. Restore Personal Files: After OS installation is complete and booted into Windows 11, and then copy all personal data files back to documents, pictures, etc.
16. Activate Windows 11: using the COA ( AKA - 5x5) Activation Key that came with your Windows 11 Pro purchase.
    1. Note: If your PC cannot use TPM 1.2 and Win11 Security Pre-requisites were Disabled within Rufus during media creation then you might not receive all Windows 11 Security Updates.
17. Done

Hope this helps and good luck. Best to try with a test PC first (just don't activate the test PC )