Error "Out of Video Memory try allocating render resource"

I began using 4.18, and updated to 4.20, then UE suddenly won’t open.
8gb of RAM. Everything ran fine under 4.18

It is very frustrating.

Wiped the computer thinking this would free up the magical space, but it did nothing. Reloaded UE, same problem.

In doing good searches, I see that many other people have dealt with this in some form or fashion. I understand that other people have had problems with video memory, but why would 4.18 work for me, but 4.20 not?