A Google search for “ArgumentNullException” “CompactHandler” “Unexpected difference” led me to
Value can not be null during compress of backup dir #4252 which was a bit uncertain, but pointed to
Ideas about “System.ArgumentNullException: Value cannot be null.”, “Parameter name: path”
Revert incorrect disposal of IndexVolumeWriter #4137 might be fix on Mar 21, 2020, so should be in
2.0.5.104_canary_2020-03-25, even if I can’t specifically find a mention of the fix in that release note.