A customer was trying to backup Exchange 2010 with IBM Tivoli Flash Copy Manager and encountered the error below, while trying to browse the databases. The server was running Exchange 2010 SP1 UR5 on 2008 R2 and hosted only public folder database. The Tivoli was version 6.1.2 and FCM v2.2
The reason for this error is that FCM expects a mailbox database to be mounted on the Exchange server, even if it is a dedicated public folder server. This is a known issue/bug and is addressed here
Once a mailbox database was created, the error went away and FCM could browse the store.