FileServerVssAgent fail to finish the shadow copy expose in 30 minutes.
The FileServerVssAgent must finish the expose within 30 minutes. If the shadow copy device is not ready to expose within 30 minutes, FileServerVssAgent will event log this error and return timeout error to the client. Upon receiving of this error, client will abort the shadow copy creation.
Check the VSS and its 3rd party hardware provider event log. Retry and make sure the PostSnapshot is completed 30 minutes.