ISTA-D 4.39.20 fails to start

[BMWX5]

Hi!

I have a German ISTA-D 4.39.20 which fails to start with:

"Failed To Start ISTA. Please Make Sure Your ISTA Configuration is Valid".

I used it last may 2023 and it worked, my OS is Windows 11.
I have no installation files. What could I try to make it run again?

Thanks, Anna