I have my backup going to Google Drive set at default number-of-retries now. Fatal failure mail told me this:
Failed: The remote server returned an error: (403) Forbidden.
Details: System.Net.WebException: The remote server returned an error: (403) Forbidden.
at Duplicati.Library.Main.BackendManager.List()
at Duplicati.Library.Main.Operation.FilelistProcessor.RemoteListAnalysis(BackendManager backend, Options options, LocalDatabase database, IBackendWriter log, IEnumerable`1 protectedFiles)
at Duplicati.Library.Main.Operation.FilelistProcessor.VerifyRemoteList(BackendManager backend, Options options, LocalDatabase database, IBackendWriter log, IEnumerable`1 protectedFiles)
at Duplicati.Library.Main.Operation.BackupHandler.PreBackupVerify(BackendManager backend, String protectedfile)
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:
2021-10-04 07:01:50 -04 - [Error-Duplicati.Library.Main.Operation.BackupHandler-FatalError]: Fatal error
System.Net.WebException: The remote server returned an error: (403) Forbidden.
at Duplicati.Library.Main.BackendManager.List()
at Duplicati.Library.Main.Operation.FilelistProcessor.RemoteListAnalysis(BackendManager backend, Options options, LocalDatabase database, IBackendWriter log, IEnumerable`1 protectedFiles)
at Duplicati.Library.Main.Operation.FilelistProcessor.VerifyRemoteList(BackendManager backend, Options options, LocalDatabase database, IBackendWriter log, IEnumerable`1 protectedFiles)
at Duplicati.Library.Main.Operation.BackupHandler.PreBackupVerify(BackendManager backend, String protectedfile)
at Duplicati.Library.Main.Operation.BackupHandler.<RunAsync>d__20.MoveNext()
You can try raising your retries as a workaround. I kept mine low so I can look for any odd breakage when retries run out. I don’t know why Google Drive does this, but it did it for awhile to get past all 5 of its retries.
This backup is hourly, and it takes a lot of backups before I have one fail, even on a low retry count. Yours does this more often. There has been talk of trying to gather additional information from failure responses (sometimes I guess there’s more detail), but until a developer can do that (developer volunteers are few), Network Tracing in the .NET Framework is one way to get a clear text vew of everything (including private information, so be careful of what you post if you’re willing to give this a try to see what more Google said).
After a failure and some more minutes waiting, does it then run? For me, Google eventually gets over it…