Backups fails with unexpected filesize to Synology using FTP

Hi I installed duplicati on 2 PCs and have on each of them several backup-jobs which are sending the files to my Synology NAS an another location via ftp-transfer.
Some of the Jobs running well, but I have 2 jobs which create problems.

Job 1

Failed: Die Datei duplicati-20180604T211756Z.dlist.zip wurde hochgeladen, aber die zurückgegebene Dateigröße ist 43560 und erwartet wurde 146672
Details: Duplicati.Library.Interface.UserInformationException: Die Datei duplicati-20180604T211756Z.dlist.zip wurde hochgeladen, aber die zurückgegebene Dateigröße ist 43560 und erwartet wurde 146672
   bei Duplicati.Library.Main.Operation.BackupHandler.HandleFilesystemEntry(ISnapshotService snapshot, BackendManager backend, String path, FileAttributes attributes)
   bei Duplicati.Library.Main.Operation.BackupHandler.RunMainOperation(ISnapshotService snapshot, BackendManager backend)
   bei Duplicati.Library.Main.Operation.BackupHandler.Run(String[] sources, IFilter filter)
   bei Duplicati.Library.Main.Controller.<>c__DisplayClass17_0.<Backup>b__0(BackupResults result)
   bei Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Action`1 method)

Job2

Failed: Die Datei duplicati-i0c50803ab897471e9f8f2c37eabc0e64.dindex.zip wurde hochgeladen, aber die zurückgegebene Dateigröße ist 43560 und erwartet wurde 69579
Details: Duplicati.Library.Interface.UserInformationException: Die Datei duplicati-i0c50803ab897471e9f8f2c37eabc0e64.dindex.zip wurde hochgeladen, aber die zurückgegebene Dateigröße ist 43560 und erwartet wurde 69579
   bei Duplicati.Library.Main.Operation.BackupHandler.HandleFilesystemEntry(ISnapshotService snapshot, BackendManager backend, String path, FileAttributes attributes)
   bei Duplicati.Library.Main.Operation.BackupHandler.RunMainOperation(ISnapshotService snapshot, BackendManager backend)
   bei Duplicati.Library.Main.Operation.BackupHandler.Run(String[] sources, IFilter filter)
   bei Duplicati.Library.Main.Controller.<>c__DisplayClass17_0.<Backup>b__0(BackupResults result)
   bei Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Action`1 method)

for both the result is the file upload was done, but the returned filesize is different than expected.
In both jobs the returned filesize is 43560!!! It means several PCs, Several Jobs, same false returned filesize. The using the same ftp as target and so the problem comes maybe from the target device (ftp-server) - but I have no idea what can it be :-/

Is there somebody who can explain me how to solve?

Thanks in advance

What version of Duplicati? I had similar problems with 2.0.3.6, i had to go back to 2.0.3.5 to fix the odd errors.

the last official 2.0.3.3_beta_2018-04-02. When somebody confirm the problem is solved by another version - I try with pleasure, but it seems not :slight_smile:

Hi @Jorg_Nestler, welcome to the forum!

If you look at the files on the NAS are they actually the 43560 size or the larger (correct) size?

(By the way, I edited your initial post by adding “~~~” before and after the error messages to help make them easier to read.)

On the NAS the size was bigger, close to the expected one.

Thanks for the update (and sorry for the delay).

@Pectojin, do you know of a way to dig into a potential issue where the destination reports a size DIFFERENT than the actual file at the destination?

I’m trying to figure out how to narrow down any of these:

  • it’s fully a destination bug (it always reports wrong size)
  • it’s a timing destination bug (size is under-reported only after initial write)
  • it’s a Duplicati API bug (we’re asking the wrong thing)
  • it’s a Duplicati processing bug (we’re getting the correct value back but then munging it somehow, like maybe using an incorrectly sized variable)

Dont worry - I know you are doing a great job and I am not the only user with support-questions :slightly_smiling_face:
Maybe it helps you to analyze. In the meanwhile I changed the settings on both PCs and I dont use the ftp/aftp transfer. Now it is using the ssh and since I changed - the problem doesnt come back. Maybe it is specific linked to the ftp - transfer.

Thanks, we try to help when we can. :blush:

Good thinking on shifting from FTP to SFTP. Not only have you helped isolate the issue to FTP (either at the Duplicati end, Synology end, or both) but you’ve moved to a more secure transfer method. :clap:

Since there were over 133k backups via FTP in May (https://usage-reporter.duplicati.com/), I’m going to guess that it’s either an issue specific to Synology or Synology+Duplicati. That still doesn’t explain why only some of your jobs are having the problem, but I never it was a GOOD guess. :slight_smile:

Since you’ve found a workaround I don’t know how much time we’ll spend trying to debug the problem, but in case the opportunity arises it would be handy to know what version of the Synology DSM you were using when the FTP related filesize issues happened.

(By the way, I edited the topic title to reflect that the error only seems to happen with FTP to the Synology.)

Hi,

the DSM is:
DSM 6.1.7-15284

but by using sftp - all work fine for me. It means dont waste time for debugging the issue, when I am the only guy with this problem - it makes no sense :slight_smile:

1 Like

I have the same issue with a WD My Cloud (Firmware 2.30.193).

  • Using FTP did not work at all (but worked well with Duplicati 1.3.4). Error 553 - invalid filename, no file uploaded.

  • With “FTP (Alternativ)” files got uploaded, but quickly led to the above errors about the file size. Sizes of uploaded files on WD My Cloud looked right (via FileZilla).

  • Using SFTP (SSH) seems to work (backup is still running).

same here for via ftp on a Fritzbox NAS (full updated OS 7.14) with Duplicati - 2.0.4.23_beta_2019-07-14

If your NAS has ssh and it works, that might be the best plan. Alternatively, does FTP (Alternative) stop doing the complaint about the wrong length if you use –disable-upload-verify=true? If so, you can either stick with the setting or wait for the next Beta. v2.0.4.32-2.0.4.32_canary_2019-10-24 fixed a bug where file length was read prematurely, so it would look like it was too short, but actually wound up fine – later.

Debugging FTP would be another option. Does “Test connection” button work, or complain about name? One of these clients didn’t like spaces in names, IIRC, but I don’t recall the FTP version, or how it failed.