"A task was canceled" error Duplicati - 2.0.3.9_canary_2018-06-30

Hi,

The operation Backup has failed with error: A task was canceled.

I suspect “That message implies the job was manually cancelled” is true but accidental, and above shows the Message from the low-level .NET System.Threading.Tasks.TaskCanceledException seen in the post. There’s maybe a very indirect mapping of low-level .NET Tasks to high-level Duplicati operations.

The posted CoCoL.ChannelExtensions.WaitForTaskOrThrow reference is probably from
https://github.com/kenkendk/cocol/blob/master/src/CoCoL/ChannelExtensions.cs#L98

I’ve gotten a few “A task was canceled” in my 4 months of server logs. The first one was:

2018-07-19 14:39:59 -04 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Backup has failed with error: A task was canceled.
System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at CoCoL.ChannelExtensions.WaitForTaskOrThrow(Task task)
   at Duplicati.Library.Main.Controller.<>c__DisplayClass13_0.<Backup>b__0(BackupResults result)
   at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Action`1 method)

and that followed a flood of per-file CoCoL exceptions like:

2018-07-19 14:39:52 -04 - [Warning-Duplicati.Library.Main.Operation.Backup.MetadataPreProcess.FileEntry-ProcessingMetadataFailed]: Failed to process entry, path: C:\Users\Ted\Documents\size test\short.txt
CoCoL.RetiredException: The channel is retired
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at CoCoL.Channel`1.<WriteAsync>d__30.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Duplicati.Library.Main.Operation.Backup.MetadataPreProcess.<>c__DisplayClass2_0.<<Run>b__0>d.MoveNext()

It’s not clear exactly what these are telling me, but Duplicati emailed me the fatal error. I too wasn’t doing any manual cancellations, but this began when I was investigating to help look into Skip-files-larger-than ignored.