The PurgeUnreferencedFvItemQueue is used by external vaulting and Upload to Cache to track and clean up information about the outdated or failed attempts to perform upload of content to cache on the master site. The queue contains only one item at any time.

A failed queue entry is an indication that some outdated information about uploading to cache could not be removed.

Checking for failed entries in this queue is not necessary. If the entry in the queue is in the failed state, it will be recreated during the next startup of the method server.