Corrupt Word file via nextcloud sftp external storage

Hello community,

I have a nextcloud V20.0.8 by my hoster and I have connected this nc with my Synology NAS Station.

When I access the Microsoft Word file via the WebDAV, it often happens that a non-compliant character has been recognized and I should repair the file.
If I access the same Microsoft Word File direct from my NAS the file is not corrupt and opens normally.

Does anyone have any idea why that is?

hank you very much!

If you download the file from the webinterface and open it then, does it work?

If you use the webdav from microsoft, that has a few issues. The non-compliant character refers to something in the file or to the filename?


now I have run additional tests:
If the file is stored by my hoster and I access via WebDAV, the file is OK.
If the file is stored by my Synology and I access via WebDAV, the file is corrupt.

The Synology Diskstation is connected with SFTP

Here is the correct and the corrupte file:

Thank you!

No it do not work.

I use Windows 10.

I carried out additional tests and can now reproduce the malfunction.

  1. I connect my WebDAV String from nextcloud and connect it to a drive letter (F:) in my file-explorer (windows 10)
  2. I create a word or excel file local on my drive C:
  3. I copy the file to nextcloud (external storage → Synology)
  4. I open the file from F: (WebDAV) => all is fine
  5. I edit the document and save back
  6. I open the same file again on F: (WebDAV) the file is corrupt
  7. I open the file from my Synology disc station, the file is OK


Can you try to use a different webdav client (winscp). Just to know if the webdav on server or client side is more likely to create the problem.

I have downloaf WinSCP 5.17.10, but it is the same behavior.

Meanwhile, I think WebDAV is not the problem. If the document storing at the harddisc by my hoster, the file is fine.
Only - after editing - if the file is stored on my Synology Disc Station (via App “External Storage Support” with sftp, and I was reopen the file, the file is corrupt.

BUT - now it gets strange - if I open the modified file directly from Synology, it is fine.

So I think the file someware at the way from my “Synology Discstation” => nextcloud (via SFTP “External Storage Support”) => my Windows 10 Client with WebDAV becomes defective.


If you have the version on both sides, you can compare the hashsum if the files are identical. If there is a difference, you can check what has changed. The logfiles don’t show anything, no timeout. You have this problem on different documents, different sizes and other file formats?

The file is not equal:

I have compare the files with the program fc from Windows:

No log entry and no timeout.

I have tried also with LibreOffice files and here is the same effect.
Perhaps it is a problem with compressed file? I know that *.xlsx and *.docx is a zip file but is libreOffive files also zip files?
There is not context with the size of a file.



Doesn’t anyone have any idea where to look for the fault?



meantime, I have taken a test instance from nextcloud (v20) by ionos. At this instance, I have also connected my Synology DiskStation with sftp and the same user and password.
And here are the office documents correct.
Only by my nc21 the office documents are corrupt.
Does anyone have any ideas how I can fix this?

Thank you!


meantime, I have update to version 21.0.2 and the error is still there.
Have nobody a hint for me?