I don't know but thank your lucky stars!

I had many simulations, drapes, renders and shader changes that I deliberately aborted. Then....I had some that were involuntarily stopped by a frozen C6. After that, problems escalated, more and more crashed simulations, etc., and no one could help me until the above message.

At one point I completely reinstalled Carrara. Did not help, until I emptied that folder.

If you get any funny business from Carrara, check that folder!

::::: Opera :::::