Error while backup

What does this errors mean?

  • 2024-06-21 01:16:17 +02 - [Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile]: Failed to process file HashMismatchException: Fehlerhafter Hash-Wert für Datei “C:\Users\xxxxx\AppData\Local\Temp\dup-e9519f2f-ade6-4962-ab3e-6c91c123777b”, gespeicherter Hash: KCIRpwQaSfelk8wDrFprUpSkYQpWJnviui+nrsI6Nxg=, aktueller Hash gGqqeLIQEv7dq1xjFmEIKzJAsVW8zlyQem2Aus5Yq3w=
  • 2024-06-21 01:16:17 +02 - [Error-Duplicati.Library.Main.Operation.TestHandler-Test results]: Verified 3 remote files with 1 problem(s)

I have tried clear and repair my database but these errors keep returning

Verifying backend files explains this verification test which appears to be detecting corrupted files. Language could be simpler, but Cryptographic hash function is sort of like a fingerprint of that file.
Duplicati database knows what it should be, but upon download the file does not give the answer.

If they are dblock files, that might not be noticed or cleared by database Recreate which uses dlist and dindex files ideally. The problem with bad dblock file is that you may have lost source file data.

What is the Storage Type of the destination? Any idea how reliable it is against corruption of files?

You might eventually decide to do a thorough files survey, for example using The TEST command.

As described by @ts678 this means that the remote file has been modified. This is usually a sign of damaged remote storage and will likely mean that parts of your backup cannot be restored.