Fatal error: Detected non-empty blocksets with no associated blocks


What --log-file-log-level did you use? I suggest verbose.

If verbose is too much, try Information

What would be helpful (but it’s a lot of steps) is

  1. Starting with a working backup job
  2. Turn on --log-file-log-level (as you have)
  3. experience non-empty blocksets error (well, I hope you don’t, I hope no one does, but if you do)
  4. perform sql query in database browser
  5. Find 5 of 10 files “around” where the failing file was
  6. go back to logfile and search for those files. This is likely from previous runs, not the current that received the error.
  7. hopefully something in the logfile will be revealing

Fatal error System.Exception: Detected non-empty blocksets with no associated blocks!

@thomasp your PathTooLongException appears to be a known bug with --usn-policy. See this post.

I updated my reply #16 with an edit to this effect.


As a followup, I ended up adding filters to prevent Duplicati from trying to backup both the temp directory as well as the directory where Duplicati’s database was being kept, along with a few other directories containing some Windows files that were constantly changing and didn’t need to be backed up. Then I recreated the database. It’s been running for somewhere around a week and a half without a problem. Seeing as how this error previously kept being generated within a day or two of recreating the database, and that happened several times, I feel pretty confident that these exclude filters are what is fixing it for me and should point the developers toward fixing it in the code.


Interestingly, as soon as I turned on the most verbose log level for a job where this had happened, this error has stopped happening to me. So, either I got lucky so far, or an update has fixed it?


Are you using OneDrive backend?

I have two backups to two different OneDrive accounts running for more than a year. 15 days ago, one of them failed with “Detected non-empty blocksets” error. Repair database don’t change anything, and recreate database (it took one week) turns the error to “You have attempted to change the block-size on an existing backup”.
I’ve deleted the backup (bye bye 6 months of backup history) and recreated the task and now I’m getting “Object reference not set to an instance of an object” in different files everytime I try to run the task.

The other backup task is working right all the time so I suspect the OneDrive account. I had other bad experiences in the past with OneDrive. Microsoft guys changes something or something in some servers gets unstable and stops working (and long after they fix it and works again)


I’m using local disk backup, and just today had this problem once again. It just randomly hits you. After running manual repair, backups work again.