WebDav fails with 405 error on Synology NAS

1

I have one historic Raspberry PI running Duplicati on Docker: 2.2.0.3 - 2.2.0.3_stable_2026-01-06. WebDav was configured well over 12 months ago and is working well.

I recently rebuilt a 2nd Raspberry PI, clean install of Bookworm OS, Docker 29.1.3 and Duplicati v2.2.0.3_stable_2026-01-06-ls276. I’ve also added Dupicati to a 3rd Raspbery PI that was set up some months ago from a fresh install. It too has the same version of Duplicati.

The latest release seems to have two faults:

  • The settings entered into the Webav server configuration screen are not persistent. Move away and back and the settings are gone. Ditto if you return to that screen after saving it.

  • WebDav does not work on the latter two devices. Testing the server (with exactly the same settings as always used) results in a 405 Method not allowed error

The server is obviously working in that Raspberry PI 1 continues to function. Further, server settings for OneDrive are retained, even after saving, all three devices. The only distinction is that the first Raspberry PI was setup quite some time ago and has had constant updates; other devices are more recent. OneDrive works as expected across all three devices.

Any suggestions?

2

Further t the above, here are the differences between the 1 working Raspberry Pi a the 2 non-working PIs:

Working:

"TargetURL": "webdav://192.168.xxx.xxx:5005",
"DBPath": "/config/ZCZKEFQEUR.sqlite",

Not Working
“TargetURL”: “webdav://192.168.xxx.xxx:5005/raspberrypi%5Cduplicati%5C<pi_hostname>%5Chome%5Chourly?auth-username=\u0026auth-password=<some_pwd>”,
“DBPath”: “/config/UWYXWJQNAB.sqlite”,

3

That would have started on the old UI. It’s still available in 2.2 via Settings.

You can’t put two backups in a folder easily. Maybe you mean other settings.

What authentication does WebDAV want? Working setup showed none at all.
Not working one showed redacted auth-password and blank auth-username.

BTW if this is peeking inside an export file, you can also look at the GUI view:

image
image341×148 5.62 KB

Can’t get this. Please post simple and safe Destination setup that gets this.

Since I guess you know your settings well, do they work if entered in old UI?
New UI, being new, might have bugs, but the key is to figure out their nature.

Another good way to compare what a UI made is “Export As Command-line”.
One should be able to take the URL from that to BackendTool in an OS shell.

WebDAV Destination shows the usual format, before shell or JSON escapes.
The way of asking for TLS use has changed, but I don’t know if you use TLS.
I think the old mthod was appending an s, so webdavs, and I don’t see that.