I got this error a few weeks ago right after I installed Trados Studio 2021 and MulitTerm 2021. I tried the suggested renaming the folder and repairing, etc. to no avail. I installed a Windows update shortly thereafter and the problem went away. But it soon came back. Each time I install an update of either Windows 10 or MultiTerm 2021, the problem goes away, but it always comes back in a day or two. Also, when I tried to save a termbase entry when I'm in Trados, I get: "Object reference not defined for an instance of an object.".