I think I am also getting the same issue.

I have imported 281 products out of 372 products manually then results showing for my category on the frontend is fine. If I inserted beyond 281 then it is showing the same error i.e.

A non-recoverable error occurred.

then I also checked with pages 3 and 4. It is being opened but having issues with pages 1 and 2 on which it is giving errors.