Backup started failing "non-empty blocksets with no associated blocks"


Backup fail to start with error:
System.AggregateException: Detected non-empty blocksets with no associated blocks!

Not long ago I rebuild the database because of some errors. I am using

Should I rebuild again?


This error is coming out of database VerifyConsistency step, but I’m not exactly sure how we’d get into this situation in the first place.

I’d suggest a Repair first (just because it’s likely faster) to see if that resolves it and if not then try another rebuild.


I just had the same error.

  • My backup was working great. It included a lot of directories, including “C:\user” and all subdirectories.
  • I deleted some source files from the backup set (via the ‘edit’ option). Specifically, I deleted a cache directory from deep within the windows c:\USER…\appdata\mozilla… tree (as it was just continually backing up new cache files pointlessly)
  • On the very next (and every subsequent) backup, I get the above error.
  • I tried editing the job again, and the strange part is that the changes I made to the directory selections didn’t seem to ‘stick’. Deleting the whole C:\user directory didn’t help, and adding it back didn’t help either.

It may be pure co-incidence, but my gut tells me that deleting directories from the source list is related to the error.