Mac mini (2012) 10.13.6 update error

[Cave Man]

Just tried to update from 10.13.5 to 10.13.6 using the App Store and it borked my system (128 GB SSD + 1.5 TB HD as a Fusion volume). Had to do a restore from Time Machine. Next, I downloaded the 10.13.6 Combo Update and upon reboot was presented with the error message:

Mac OS could not be installed on your computer:
Invalid Request

Any idea how to get around this problem?

 

[BLUEDOG314]

If you have already done a Time Machine restore and know you have a working backup, I would say use internet recovery (CMD+Option+R) to erase and reinstall macOS as it will take you to 10.13.6, then use your backup.