I discovered in a Lync 2013 enterprise environment that Export-CSUserData backups did not include the full count of all user data within an enterprise Front End Pool. Even though the powershell scripts that included this command completed successfully the files themselves on contain a partial user count when attempting a Update-CSUserData -UserFilter restore.
After some diagnosis I discovered that if a pool contains any user that has a forward slash “/” in the SipAddress that will cause the Export-CSUserData command to stop mid-progress of the export resulting in only partial user data being available to restore when needed. Example error:
Export-CSUserData : “urn:upc:SipAddressContainsA/ForwardSlash@LyncLead.com” is not a valid uniform resource name (URN).
After moving all User accounts that contained a forward slash my backup was 100% successful.
Moral of the story:
Even though a forward slash technically is not noted as one of the illegal characters for SIP addresses, it should be on the no go list due to this reason.