Help! Why did this fatal error occur?

Support
1

I set the block size to 64MB and the remote Volume Size to 1GB, why am I getting this fatal error every time?I’m using WebDAV for backup. Is this a cloud-based issue or a problem with my local settings?The following is the complete log.

{
“DeletedFiles”: 0,
“DeletedFolders”: 0,
“ModifiedFiles”: 0,
“ExaminedFiles”: 261,
“OpenedFiles”: 254,
“AddedFiles”: 254,
“SizeOfModifiedFiles”: 0,
“SizeOfAddedFiles”: 140365779026,
“SizeOfExaminedFiles”: 161053438657,
“SizeOfOpenedFiles”: 140365779026,
“NotProcessedFiles”: 0,
“AddedFolders”: 0,
“TooLargeFiles”: 0,
“FilesWithError”: 0,
“TimestampChangedFiles”: 0,
“ModifiedFolders”: 0,
“ModifiedSymlinks”: 0,
“AddedSymlinks”: 0,
“DeletedSymlinks”: 0,
“PartialBackup”: false,
“Dryrun”: false,
“MainOperation”: “Backup”,
“CompactResults”: null,
“VacuumResults”: null,
“DeleteResults”: null,
“RepairResults”: null,
“TestResults”: null,
“ParsedResult”: “Fatal”,
“Interrupted”: false,
“Version”: “2.2.0.0 (2.2.0.0_stable_2025-10-23)”,
“EndTime”: “2025-10-31T22:28:25.7186456Z”,
“BeginTime”: “2025-10-31T14:26:05.31563Z”,
“Duration”: “08:02:20.4030156”,
“MessagesActualLength”: 647,
“WarningsActualLength”: 8,
“ErrorsActualLength”: 2,
“Messages”: [
“2025-10-31 22:26:05 +08 - [Information-Duplicati.Library.Main.Controller-StartingOperation]: 操作 Backup 已开始”,
“2025-10-31 22:26:10 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: List - Started: ()”,
“2025-10-31 22:26:16 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: List - Completed: ()”,
“2025-10-31 22:36:04 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b6f58c5fb03f042fb8899d63806101427.dblock.zip.aes (961.11 MiB)”,
“2025-10-31 22:36:08 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-bb830359fac234d4dabfd8471fa591ddd.dblock.zip.aes (972.17 MiB)”,
“2025-10-31 22:36:10 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-bd1540844f9ea44c4b35758410e4a65f2.dblock.zip.aes (970.48 MiB)”,
“2025-10-31 22:36:17 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b3b9aba10e4ea41f8b4354f32d97188d5.dblock.zip.aes (980.29 MiB)”,
“2025-10-31 22:48:06 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-bd1540844f9ea44c4b35758410e4a65f2.dblock.zip.aes (970.48 MiB)”,
“2025-10-31 22:48:06 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-i0d5f86351b0247fe94fd9d99275a5b24.dindex.zip.aes (3.98 KiB)”,
“2025-10-31 22:48:08 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-i0d5f86351b0247fe94fd9d99275a5b24.dindex.zip.aes (3.98 KiB)”,
“2025-10-31 22:48:08 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b33c8898221464196b5e487101ae69065.dblock.zip.aes (995.64 MiB)”,
“2025-10-31 22:50:26 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-b6f58c5fb03f042fb8899d63806101427.dblock.zip.aes (961.11 MiB)”,
“2025-10-31 22:50:26 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-i7c0d4afd3ad14fc8820af50a70c21124.dindex.zip.aes (3.29 KiB)”,
“2025-10-31 22:50:29 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-i7c0d4afd3ad14fc8820af50a70c21124.dindex.zip.aes (3.29 KiB)”,
“2025-10-31 22:50:31 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b7a73ebe6915548da84a987488281092a.dblock.zip.aes (962.03 MiB)”,
“2025-10-31 22:50:31 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-bb830359fac234d4dabfd8471fa591ddd.dblock.zip.aes (972.17 MiB)”,
“2025-10-31 22:50:31 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-i8de12b3b68ca4fd08f5fe8c03e088832.dindex.zip.aes (4.53 KiB)”,
“2025-10-31 22:50:33 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-i8de12b3b68ca4fd08f5fe8c03e088832.dindex.zip.aes (4.53 KiB)”,
“2025-10-31 22:50:33 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b9e28d23f15a3428ca404c8d6c13822d9.dblock.zip.aes (1,002.56 MiB)”,
“2025-10-31 22:50:57 +08 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-b3b9aba10e4ea41f8b4354f32d97188d5.dblock.zip.aes (980.29 MiB)”
],
“Warnings”: [
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerHandlerFailure]: Error in handler: Error while copying content to a stream.\r\nHttpRequestException: Error while copying content to a stream.”,
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerDisposeWhileActive]: Terminating 3 active uploads”,
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerDisposeError]: Error in active upload: Cancelled”,
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerDisposeError]: Terminating, but 2 active upload(s) are still active”,
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerDisposeError]: Error in active upload: Cancelled”,
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerDisposeError]: Terminating, but 1 active upload(s) are still active”,
“2025-11-01 06:28:24 +08 - [Warning-Duplicati.Library.Main.Backend.Handler-BackendManagerDisposeError]: Error in active upload: Cancelled”,
“2025-11-01 06:28:25 +08 - [Warning-Duplicati.Library.Main.Backend.BackendManager-BackendManagerShutdown]: Backend manager queue runner crashed\r\nAggregateException: One or more errors occurred. (Error while copying content to a stream.)”
],
“Errors”: [
“2025-11-01 06:28:25 +08 - [Error-Duplicati.Library.Main.Operation.BackupHandler-FatalError]: Fatal error\r\nHttpRequestException: Error while copying content to a stream.”,
“2025-11-01 06:28:25 +08 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Backup has failed\r\nHttpRequestException: Error while copying content to a stream.”
],
“BackendStatistics”: {
“RemoteCalls”: 293,
“BytesUploaded”: 136888860908,
“BytesDownloaded”: 0,
“FilesUploaded”: 268,
“FilesDownloaded”: 0,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 23,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 0,
“KnownFileSize”: 0,
“KnownFilesets”: 0,
“LastBackupDate”: “0001-01-01T00:00:00”,
“BackupListCount”: 0,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“AssignedQuotaSpace”: -1,
“ReportedQuotaError”: false,
“ReportedQuotaWarning”: false,
“MainOperation”: “Backup”,
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.2.0.0 (2.2.0.0_stable_2025-10-23)”,
“EndTime”: “0001-01-01T00:00:00”,
“BeginTime”: “2025-10-31T14:26:05.3158708Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
}

2

Did it work with smaller sizes on any Duplicati release? If so, which one?

The job log one-line message drops details. Please check the server log.

About Duplicati → Logs → Stored and click error that seems like this one.

After that, the developer may have comment, but now is a very busy time.

I can’t find any exactly similar reports. Unique cases are harder to handle.
Fortunately (maybe not for you) reproducible ones can test various things.
Perhaps some timeout needs to go up, especially for that big volume size.

3

Hello, I’ve only used the latest version of Duplicati, which is 2.2.0.0_stable_2025-10-23. I don’t know about the earlier versions. This is the server log.

  1. System.Net.Http.HttpRequestException: Error while copying content to a stream.

  2. —> System.IO.IOException: Unable to write data to the transport connection: 远程主机强迫关闭了一个现有的连接。.

  3. —> System.Net.Sockets.SocketException (10054): 远程主机强迫关闭了一个现有的连接。

  4. — End of inner exception stack trace —

  5. at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)

  6. at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)

  7. at System.Net.Http.HttpConnection.RawConnectionStream.WaitWithConnectionCancellationAsync(ValueTask task, HttpConnection connection, CancellationToken cancellationToken)

  8. at System.Net.Security.SslStream.g__CompleteWriteAsync|157_1[TIOAdapter](ValueTask writeTask, Byte[] bufferToReturn)

  9. at System.Net.Security.SslStream.WriteAsyncChunked[TIOAdapter](ReadOnlyMemory`1 buffer, CancellationToken cancellationToken)

  10. at System.Net.Security.SslStream.WriteAsyncInternal[TIOAdapter](ReadOnlyMemory`1 buffer, CancellationToken cancellationToken)

  11. at System.IO.Stream.g__Core|27_0(Stream source, Stream destination, Int32 bufferSize, CancellationToken cancellationToken)

  12. at System.Net.Http.HttpContent.g__WaitAsync|56_0(ValueTask copyTask)

  13. — End of inner exception stack trace —

  14. at Duplicati.Library.Main.Backend.BackendManager.Handler.ExecuteWithRetry(PendingOperationBase op, CancellationToken cancellationToken)

  15. at Duplicati.Library.Main.Backend.BackendManager.Handler.ReclaimCompletedTasks(List`1 tasks)

  16. at Duplicati.Library.Main.Backend.BackendManager.Handler.EnsureAtMostNActiveTasks(Int32 n, List`1 tasks)

  17. at Duplicati.Library.Main.Backend.BackendManager.Handler.EnsureAtMostNActiveTasks(Int32 uploads, Int32 downloads)

  18. at Duplicati.Library.Main.Backend.BackendManager.Handler.Run(IReadChannel`1 requestChannel)

  19. at Duplicati.Library.Main.Backend.BackendManager.PutAsync(VolumeWriterBase volume, IndexVolumeWriter indexVolume, Action indexVolumeFinished, Boolean waitForComplete, Func`1 onDbUpdate, CancellationToken cancelToken)

  20. at Duplicati.Library.Main.Operation.Backup.DataBlockProcessor.<>c__DisplayClass0_0.<b__0>d.MoveNext()

  21. — End of stack trace from previous location —

  22. at Duplicati.Library.Main.Operation.Backup.DataBlockProcessor.<>c__DisplayClass0_0.<b__0>d.MoveNext()

  23. — End of stack trace from previous location —

  24. at CoCoL.AutomationExtensions.RunTask[T](T channels, Func`2 method, Boolean catchRetiredExceptions)

  25. at Duplicati.Library.Main.Backend.BackendManager.Handler.Run(IReadChannel`1 requestChannel)

  26. at Duplicati.Library.Main.Backend.BackendManager.Handler.<>c__DisplayClass14_0.<b__0>d.MoveNext()

  27. — End of stack trace from previous location —

  28. at CoCoL.AutomationExtensions.RunTask[T](T channels, Func`2 method, Boolean catchRetiredExceptions)

  29. at Duplicati.Library.Main.Operation.BackupHandler.RunMainOperation(Channels channels, ISourceProvider source, UsnJournalService journalService, BackupDatabase database, IBackendManager backendManager, BackupStatsCollector stats, Options options, IFilter filter, BackupResults result, ITaskReader taskreader, Int64 filesetid, Int64 lastfilesetid)

  30. at Duplicati.Library.Main.Operation.BackupHandler.RunAsync(String[] sources, IBackendManager backendManager, IFilter filter)

  31. at Duplicati.Library.Main.Controller.<>c__DisplayClass22_0.<b__0>d.MoveNext()

  32. — End of stack trace from previous location —

  33. at Duplicati.Library.Utility.Utility.Await(Task task)

  34. at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Func`3 method)

  35. at Duplicati.Library.Main.Controller.Backup(String[] inputsources, IFilter filter)

  36. at Duplicati.Server.Runner.RunInternal(Connection databaseConnection, EventPollNotify eventPollNotify, INotificationUpdateService notificationUpdateService, IProgressStateProviderService progressStateProviderService, IApplicationSettings applicationSettings, IRunnerData data, Boolean fromQueue)

Is the problem with the cloud or with my local machine?I also discovered a bug: the volume size and block size can both be set to 1GB, and then the program’s memory commit size will reach an astonishing tens or even hundreds of GB.

4

Thanks for the stack trace. Maybe the developer can make a guess.
The one thing that seems clear is that the remote closed connection.

Google for socket exception 10054 gives many things it might mean.

A more definite analysis might need protocol analysis that isn’t likely.
I’m assuming you’re on an encrypted https connection over Internet?

Rather than blame the remote, question is why it decided to go away.
Possibly Duplicati did something it disliked. Maybe it got tired of work.

Some systems do throttle (slow work) after one has done lots of work.
Is this a private server, or some company maybe limiting your usage?

Are you seeing any pattern? Does it fail randomly, or at typical times?

Have you tried a smaller volume size? A gigabyte seems rather large.

You could also increase all the timeouts possible to see if that helps it.

is what I thought the rule was, but dev might know. If you configure huge, you might get huge. Unclear if there’s a bug involved, but the dev might comment. I’d have hoped huge is on disk.

EDIT 1:

If you want a shot-in-the-dark of increasing timeouts, CLI help for webdav says defaults are:

  --short-timeout = 30s
    The timeout in seconds for short operations like delete and create folder
  --list-timeout = 10m
    The timeout in seconds for listing files and folders
  --read-write-timeout = 30s
    The timeout in seconds for read and write operations. If no activity is detected in this interval, a timeout error is raised

and you could try raising all of them to some number of minutes longer than usually needed.