Win8.1 system prompts can not verify product key solution tutorial

After Microsoft released the official version of win10, users have upgraded to Win10 system. After the upgrade, Win10 is not easy to use. Because the Windows.old file has been deleted, it cannot be directly returned to Win8.1. When installing Win8.1 using the CD, the installer is suddenly interrupted, and the product key cannot be verified (as shown below). How to solve this problem? Continue to share the detailed solutions.

The method is as follows:

1, Win+X opens a command prompt (as an administrator);

2, the command prompt performs the following Command:

dism /online /Cleanup-Image /RestoreHealth & sfc /SCANNOW & for %d in (%windir%\\system32\\*.dll) do %windir%\\system32\ egsvr32.exe /s %d & pause

3. If it is not possible, it is a key problem. Win8.1 and Win10 keys can be shared. It is recommended to use Win10 key to activate.

4. If you are using a brand-configured CD, you can boot directly by pressing F12 to select the CD.

The above is the solution to install Win8.1 system prompt "can not verify the product key", I hope to help everyone!