Task stopped working after 1 year running well: ImportError: sys.meta_path is None, Python is likely shutting down

Dear all, I have a task (paired associates task) that was running well for a time. However, now sometimes the task suddenly quits in the middle of the task. Other times it works perfectly. We installed the task on different PC’s and the same error happens occasionally on different PCs. Psychopy version = 2020.2.10

We get the following error:

ImportError: sys.meta_path is None, Python is likely shutting down

I tried to google the problem, but could not find a specific solution or the reason why this error is happening sometimes, but not always.

Does anyone have an idea and can help us out?

Best regards, Sanne