Error while running backup - no data available

Support
1

Hello,

Today my daily backup to NAS has started to fail with the notification Error while running Linux on NAS

No data available : ‘/mnt/nas-backup/Linux/duplicati-20260224T160000Z.dlist.zip.aes’

The file is present and this is the corresponding log entry:

System.IO.IOException: No data available : '/mnt/nas-backup/Linux/duplicati-20260224T160000Z.dlist.zip.aes'
   at Microsoft.Win32.SafeHandles.SafeFileHandle.ThreadPoolValueTaskSource.ExecuteInternal()
--- End of stack trace from previous location ---
   at Microsoft.Win32.SafeHandles.SafeFileHandle.ThreadPoolValueTaskSource.GetResult(Int16 token)
   at System.Threading.Tasks.ValueTask`1.ValueTaskSourceAsTask.<>c.<.cctor>b__4_0(Object state)
--- End of stack trace from previous location ---
   at Duplicati.StreamUtil.TimeoutObservingStream.ReadImplAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at Duplicati.Library.Utility.Utility.CopyStreamAsync(Stream source, Stream target, Boolean tryRewindSource, CancellationToken cancelToken, Byte[] buf)
   at Duplicati.Library.Backend.File.GetAsync(String remotename, Stream stream, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetOperation.DoGetFileAsync(IBackend backend, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetOperation.ExecuteAsync(IBackend backend, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.Handler.Execute[TResult](PendingOperation`1 op, CancellationToken cancellationToken)
   at Duplicati.Library.Main.Backend.BackendManager.Handler.Execute(PendingOperationBase op, CancellationToken cancellationToken)
   at Duplicati.Library.Main.Backend.BackendManager.Handler.ExecuteWithRetry(PendingOperationBase op, CancellationToken cancellationToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetWithInfoAsync(String remotename, String hash, Int64 size, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetFilesOverlappedAsync(IEnumerable`1 volumes, CancellationToken cancelToken)+MoveNext()
   at Duplicati.Library.Main.Backend.BackendManager.GetFilesOverlappedAsync(IEnumerable`1 volumes, CancellationToken cancelToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Duplicati.Library.Main.Operation.TestHandler.DoRunAsync(Int64 samples, LocalTestDatabase db, ReusableTransaction rtr, IBackendManager backend)
   at Duplicati.Library.Main.Operation.TestHandler.DoRunAsync(Int64 samples, LocalTestDatabase db, ReusableTransaction rtr, IBackendManager backend)
   at Duplicati.Library.Main.Operation.BackupHandler.PostBackupVerification(String currentFilelistVolume, String previousTemporaryFilelist, IBackendManager backendManager, ReusableTransaction rtr)
   at Duplicati.Library.Main.Operation.BackupHandler.RunAsync(String[] sources, IBackendManager backendManager, IFilter filter)
   at Duplicati.Library.Main.Controller.<>c__DisplayClass22_0.<<Backup>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at Duplicati.Library.Utility.Utility.Await(Task task)
   at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Func`3 method)
   at Duplicati.Library.Main.Controller.Backup(String[] inputsources, IFilter filter)
   at Duplicati.Server.Runner.RunInternal(Connection databaseConnection, EventPollNotify eventPollNotify, INotificationUpdateService notificationUpdateService, IProgressStateProviderService progressStateProviderService, IApplicationSettings applicationSettings, IRunnerData data, Boolean fromQueue)

I’m not sure what the Microsoft.Win32.SafeHandles[…] line is supposed to mean, given this is Linux machine backing up to an old ReadyNAS with plenty of space and low traffic.

I’m running Duplicati with - 2.2.0.3 - 2.2.0.3_stable_2026-01-06. The source is running Ubuntu 24.04.4 LTS.

Thanks for any help.

2

Hi @coral6691, welcome to the forum :waving_hand:

Duplicati is built with .NET which has some Windows legacy stuff. The SafeHandle is essentially a pointer that is safe to use within a GC environment, so it is not tied to Windows but heavily used there.

tl;dr: Ignore the Win32 part.

The error message means that something related to the mount point is broken. The mount point says the file exists and contains data, but when Duplicati tries to read it, there is nothing there.

Could you try to unmount+mount the /mnt/nas-backup folder and see if this fixes things?

3

Hi Ken,

Thank you for replying. I did un/mount and rebooted without much luck. Of course I can go in the folder and list the files in there, so it doesn’t seem a mounting issue.

I tried to rebuild the database but got this instead:

Duplicati.Library.Interface.RemoteListVerificationException: Found 3475 remote files that are not recorded in local storage. This can be caused by having two backups sharing a destination folder which is not supported. It can also be caused by restoring an old database. If you are certain that only one backup uses the folder and you have the most updated version of the database, you can use repair to delete the unknown files.
   at Duplicati.Library.Main.Operation.FilelistProcessor.VerifyRemoteList(IBackendManager backend, Options options, LocalDatabase database, IDbTransaction transaction, IBackendWriter log, IEnumerable`1 protectedFiles, IEnumerable`1 strictExcemptFiles, Boolean logErrors, VerifyMode verifyMode)
   at Duplicati.Library.Main.Operation.BackupHandler.PreBackupVerify(Options options, BackupResults result, IBackendManager backendManager)
   at Duplicati.Library.Main.Operation.BackupHandler.PreBackupVerify(Options options, BackupResults result, IBackendManager backendManager)
   at Duplicati.Library.Main.Operation.BackupHandler.RunAsync(String[] sources, IBackendManager backendManager, IFilter filter)
   at Duplicati.Library.Main.Controller.<>c__DisplayClass22_0.<<Backup>b__0>d.MoveNext()
--- End of stack trace from previous location ---
   at Duplicati.Library.Utility.Utility.Await(Task task)
   at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Func`3 method)
   at Duplicati.Library.Main.Controller.Backup(String[] inputsources, IFilter filter)
   at Duplicati.Server.Runner.RunInternal(Connection databaseConnection, EventPollNotify eventPollNotify, INotificationUpdateService notificationUpdateService, IProgressStateProviderService progressStateProviderService, IApplicationSettings applicationSettings, IRunnerData data, Boolean fromQueue)
   at Duplicati.Server.Runner.Run(Connection databaseConnection, EventPollNotify eventPollNotify, INotificationUpdateService notificationUpdateService, IProgressStateProviderService progressStateProviderService, IApplicationSettings applicationSettings, IQueuedTask data, Boolean fromQueue)
   at Duplicati.WebserverCore.Services.QueueRunnerService.RunTask(IQueuedTask task)

So I deleted & repaired the DB and got this message:

System.IO.IOException: No data available : '/mnt/nas-backup/Linux/duplicati-20250821T105859Z.dlist.zip.aes'
   at Microsoft.Win32.SafeHandles.SafeFileHandle.ThreadPoolValueTaskSource.ExecuteInternal()
--- End of stack trace from previous location ---
   at Microsoft.Win32.SafeHandles.SafeFileHandle.ThreadPoolValueTaskSource.GetResult(Int16 token)
   at System.Threading.Tasks.ValueTask`1.ValueTaskSourceAsTask.<>c.<.cctor>b__4_0(Object state)
--- End of stack trace from previous location ---
   at Duplicati.StreamUtil.TimeoutObservingStream.ReadImplAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at Duplicati.Library.Utility.Utility.CopyStreamAsync(Stream source, Stream target, Boolean tryRewindSource, CancellationToken cancelToken, Byte[] buf)
   at Duplicati.Library.Backend.File.GetAsync(String remotename, Stream stream, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetOperation.DoGetFileAsync(IBackend backend, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetOperation.ExecuteAsync(IBackend backend, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.Handler.Execute[TResult](PendingOperation`1 op, CancellationToken cancellationToken)
   at Duplicati.Library.Main.Backend.BackendManager.Handler.Execute(PendingOperationBase op, CancellationToken cancellationToken)
   at Duplicati.Library.Main.Backend.BackendManager.Handler.ExecuteWithRetry(PendingOperationBase op, CancellationToken cancellationToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetWithInfoAsync(String remotename, String hash, Int64 size, CancellationToken cancelToken)
   at Duplicati.Library.Main.Backend.BackendManager.GetFilesOverlappedAsync(IEnumerable`1 volumes, CancellationToken cancelToken)+MoveNext()
   at Duplicati.Library.Main.Backend.BackendManager.GetFilesOverlappedAsync(IEnumerable`1 volumes, CancellationToken cancelToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Duplicati.Library.Main.Operation.RecreateDatabaseHandler.DoRunAsync(IBackendManager backendManager, LocalDatabase dbparent, Boolean updating, IFilter filter, NumberedFilterFilelistDelegate filelistfilter, BlockVolumePostProcessor blockprocessor)
   at Duplicati.Library.Main.Operation.RecreateDatabaseHandler.DoRunAsync(IBackendManager backendManager, LocalDatabase dbparent, Boolean updating, IFilter filter, NumberedFilterFilelistDelegate filelistfilter, BlockVolumePostProcessor blockprocessor)
   at Duplicati.Library.Main.Operation.RecreateDatabaseHandler.RunAsync(String path, IBackendManager backendManager, IFilter filter, NumberedFilterFilelistDelegate filelistfilter, BlockVolumePostProcessor blockprocessor)
   at Duplicati.Library.Main.Operation.RepairHandler.RunRepairLocalAsync(IBackendManager backendManager, IFilter filter)
   at Duplicati.Library.Main.Operation.RepairHandler.RunAsync(IBackendManager backendManager, IFilter filter)
   at Duplicati.Library.Utility.Utility.Await(Task task)
   at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Func`3 method)
   at Duplicati.Library.Main.Controller.RunAction[T](T result, IFilter& filter, Func`3 method)
   at Duplicati.Library.Main.Controller.Repair(IFilter filter)
   at Duplicati.Server.Runner.RunInternal(Connection databaseConnection, EventPollNotify eventPollNotify, INotificationUpdateService notificationUpdateService, IProgressStateProviderService progressStateProviderService, IApplicationSettings applicationSettings, IRunnerData data, Boolean fromQueue)

:person_shrugging:

Perhaps worth pointing out that I can still backup to the cloud (OneDrive) without issues.

4

Can you cat the files?

head -c 100 /mnt/nas-backup/Linux/duplicati-20250821T105859Z.dlist.zip.aes | base64

Or maybe just try a copy:

cp /mnt/nas-backup/Linux/duplicati-20250821T105859Z.dlist.zip.aes ~/deleteme.tmp

Makes sense if the issue is reading files on the NAS.

5

Well, it looks like it’s sorted. I tried to move an old backup subfolder from 2023 and then run another DB repair, which returned a different error (after running for nearly 1 hour!):

"2026-02-25 15:28:11 +00 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Repair has failed\nUserInformationException: Recreated database has missing blocks and 2 broken filelists. Consider using \"list-broken-files\" and \"purge-broken-files\" to purge broken data from the remote store and the database."

After purging the broken files I let the scheduled job run and it completed without errors!

:Happy bunny:

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