Just ran into this myself been using 2.0.5.1_beta since it was released.
First error show this
Failed: Path cannot be null.
Parameter name: path
Details: System.ArgumentNullException: Path cannot be null.
Parameter name: path
at Duplicati.Library.Main.BackendManager.WaitForEmpty(LocalDatabase db, IDbTransaction transation)
at Duplicati.Library.Main.Operation.CompactHandler.DoDelete(LocalDeleteDatabase db, BackendManager backend, IEnumerable`1 deleteableVolumes, IDbTransaction& transaction)
at Duplicati.Library.Main.Operation.CompactHandler.DoCompact(LocalDeleteDatabase db, Boolean hasVerifiedBackend, IDbTransaction& transaction, BackendManager sharedBackend)
at Duplicati.Library.Main.Operation.DeleteHandler.DoRun(LocalDeleteDatabase db, IDbTransaction& transaction, Boolean hasVerifiedBacked, Boolean forceCompact, BackendManager sharedManager)
at Duplicati.Library.Main.Operation.BackupHandler.CompactIfRequired(BackendManager backend, Int64 lastVolumeSize)
at Duplicati.Library.Main.Operation.BackupHandler.<RunAsync>d__20.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at CoCoL.ChannelExtensions.WaitForTaskOrThrow(Task task)
at Duplicati.Library.Main.Controller.<>c__DisplayClass14_0.<Backup>b__0(BackupResults result)
at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Action`1 method)
Log data:
2020-03-07 15:41:27 -05 - [Error-Duplicati.Library.Main.Operation.BackupHandler-FatalError]: Fatal error
System.ArgumentNullException: Path cannot be null.
Parameter name: path
at Duplicati.Library.Main.BackendManager.WaitForEmpty(LocalDatabase db, IDbTransaction transation)
at Duplicati.Library.Main.Operation.CompactHandler.DoDelete(LocalDeleteDatabase db, BackendManager backend, IEnumerable`1 deleteableVolumes, IDbTransaction& transaction)
at Duplicati.Library.Main.Operation.CompactHandler.DoCompact(LocalDeleteDatabase db, Boolean hasVerifiedBackend, IDbTransaction& transaction, BackendManager sharedBackend)
at Duplicati.Library.Main.Operation.DeleteHandler.DoRun(LocalDeleteDatabase db, IDbTransaction& transaction, Boolean hasVerifiedBacked, Boolean forceCompact, BackendManager sharedManager)
at Duplicati.Library.Main.Operation.BackupHandler.CompactIfRequired(BackendManager backend, Int64 lastVolumeSize)
at Duplicati.Library.Main.Operation.BackupHandler.<RunAsync>d__20.MoveNext()
Any attempt to run again shows similar errors as above for process in use error.
Doesn’t actually record the log process when you click on show log under the backup name. It is sending out the email report however and red warning popup.
Everything worked yesterday with the job.
Edit: Repair and run again seems to have corrected it.