Tomasz, seems we both are doing and saying the same things, my reply to you back in October
As I mentioned earlier in the thread, clearing the db in any form will fix it, but it’s not a permanent fix as the error comes back. I’m hoping that we can start testing the badger database to see if that resolves it.
As a non developer I can only make guesses and hope that something clicks with a dev. At the moment my opinion is either data isn’t being written into the database (eg, heavy load), or maybe during the compact stage something lost / corrupted. This is based on a fresh index having lots of small files then some time later they are larger. I wonder if at this point the issue creeps in.