I have reported this to support (Michelle De Guzman) and was told to report it as a bug.

When JIRA server is setup with a scheduled backup (to XML) and there is some problem with the contents of a field in the database, the backup may fail leaving behing a partial ZIP file, giving the impression that the backup completed without problems. This happend to me where one of the date fields in the database contained the value 0000-00-00, the backup job would dump the tables up to the point where it read this record and then fail. However, the backup job created a ZIP file anyway giving the impression that the backup was complete.

I was able to track down the problem by doing a manual database export using the GUI. It generated an error message and by looking at the xml file, I was able to track down the problem to the table and record.

I think that the scheduled backup should produce some warning when the job fails and most importantly should NOT create a resulting output file giving the impression that the job completed.

Thanks.