Patch installer failed to validate product key error in Windows 11/10

Besides other options, installing and upgrading Windows using ISO files has its own importance. The ISO file can be used for a clean install, a repair upgrade, or an edition upgrade. In the case of the latter two, users have reported an issue where the setup starts fine but after the ” We are preparing some things“, they get the following error:

Installer failed to validate product key

Now there is nothing we can do at this point other than a clean install, although the system can be restarted with its original settings.

Windows 11/10 installer failed to validate product key

If you encounter this problem, restart the system and try the following preliminary checks:

1]Check for updates

Check that the latest Windows updates are installed on the system.

2]Run SFC scan

Run SFC scan on the system. System File Checker helps detect and repair damaged system files.

3]Delete temporary files

Delete temporary files. To do this, press Win + R and open the Run window and type time. Press Enter to open the temporary files window and delete all files.

Repeat the process with Run commands %temp% and preread.

4]Try to upgrade using Windows Update

If it is for edition upgrade, we could do it using Windows Update instead of ISO. However, if you were considering the ISO file in the first place, you must have known your reason.

5]Log out of the domain

For domain-joined systems, temporarily remove them from the domain. A good reference to help with the same could be checked on the Microsoft website here.

6]Disable third-party antivirus software

Temporarily remove all third-party anti-virus software from the system to isolate the possibility of their interference.

If all the above mentioned attempts are not working then you can try the following fix. However, this involves a clean installation of the system, so it is advisable to back up your data well in advance.

1]Extract the contents of the ISO file and use it

Extract the ISO file using the free Ashampoo ZIP decompression software.

2]Use this Notepad file

Open a Notepad file and copy and paste the following content into it:

[EditionID]
[Channel]
Retail
[VL]
0

Save this Notepad file as ei.cfg in the Sources folder inside the setup ISO file.

3]Now run the setupexe

Run it setup.exe file to start the installation wizard. You can also try to create a bootable USB from the file and run that USB for repair or reinstallation.

Let us know if this helps you!