Job session has no errors, but the windows eventlog has several corresponding entries:
Source: VSS ID:12289
Volume Shadow Copy Service error: Unexpected error while calling GetStorageDependencyInformation. hr = 0x8007048f, The device is not connected.
this Event is logged several times consecutively, with different additional information:
Operation: Add a Volume to a Shadow Copy Set
Operation: Automatically choosing a diff-area volume, Processing EndPrepareSnapshots
and so on.