Affected Version(s):

I have personally seen this error in R9.1, but it may also be in earlier versions.

Problem Details:

When backing up Server Edition configuration, it will reach 20% and then display the following error:

Backup failed: Wait inventory pushed stage failed

Cause:

In my experience, this was caused when trying to backup to the Server Edition itself and there was not enough space on the hard drive to backup to.

Solution:

Increasing hard drive space in the server or pointing the backup to a remote server instead resolved the issue.