If you’re having troubles running Windows Update or you see the error message:
There is a system repair pending which requires reboot to complete.
Restart and run SFC again
there is an easy fix:
Either in file explorer or via command line go to C:\Windows\WinSXS and if there is a PENDING.XML file there, delete it and reboot your computer, then try Windows Update or SFC /SCANNOW again.
To delete PENDING.XML you will have to take ownership of it or at least give yourself full control NTFS permissions.
The problem was most likely caused by an unhappy shutdown of the computer which left some patches orphaned in mid-installation so you’ve got to clear out that pending file and start again.