"Object reference not set to an instance of an object" when checking files

Every time I use the "Check" function, I get this error message. It's literally impossible for me to use this function. I've checked all threads on this forum and I can't find a solution. I tried to repair the programme (in the uninstall section) but it didn't help. 

I'm using Trados Studio 2019.

Thanks for your help!

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