Snapshots may fail if a VSS writer is in a failed state. To determine which VSS writer(s) is the culprit, run the following command from an elevated command prompt:
vssadmin list writers
Find the failed VSS writer(s) using the command’s output, then restart the corresponding Windows Service. Run the VSSAdmin command once more to verify that the VSS writers are now in a stable state.
Below is a table listing VSS writers and their associated service names and display names.