Hi I chanced upon this error and I solved it also by chance, on the first try.
Here’s what I did.
– file -> import recent footage (load one of the previous footage that worked)
Thereafter, all your imports should work like before.
It was a fluke but it worked. I have not had the problem for a long time so I would not be able to advise further if it still doesnt work after trying my solution.
Nevertheless, Let me know if it works for you. I hope it helps