Thank you for your post.
First, turn off any anti-virus software as this can interfere with FileMaker Server.
Since this has been happening for 10 days, do you recall what was changed 10 days ago to your system? What activities preceded the first 791 error 10 days ago?
To get around this, stop FileMaker Server, remove the IncrementalBackup folders, reboot the server, and restart FileMaker Server. This should clear out any possible memory issues.
Keep me updated with any progress.
Many Thanks for your advice, and sorry for the late reply.
Yes, the anti virus software was disabled. We cannot remember having anything changed on the server. Removing the IncrementalBackup folders did not help either.
We now switched off incremental backups and will turn them on again with a new server version to see what will happen.