Sync & upgrade "ObjectNotFound" Error

Platform

a. Win10 1803: Desktop 1.0.216
b. Android: 1.0.336.apk
c. Win10 2004: Desktop 1.0.242
d. Win10 2004 Virtual Machine: Desktop 1.0.242

Sync Method: WebDAV (www.jianguoyun.com)

Description

I used to synchronize Joplin with Device a and Device b (listed in Platform, encrytion disabled). It worked well.
Yesterday, I just setup a new computer (Device c). When i tried to sync from webdav, an error occured:
Error: GET .sync/version.txt: The ancestors of this location does not found (Exception AncestorsNotFound) (409): <d:error xmlns:d="DAV:" xmlns:s="[http://ns.jianguoyun.com">](http://ns.jianguoyun.com%22%3E/)<s:exception>AncestorsNotFound</s:exception><s:message>The ancestors of this location does not found</s:message></d:error>

Device a and Device b are still able to sync.

Later, I setup a virtual machine (Device d), using the same .iso file and Joplin .exe with Device c. This time it showed an Upgrade page:
``
Joplin upgrade in progress…
Please wait while the sync target is being upgraded. It may take a few seconds or a few minutes depending on the upgrade. The application will automatically restart once it is completed.

Error
The sync target could not be upgraded due to an error. For support, please copy the complete content of this page and paste it in the forum: https://discourse.joplinapp.org/

The full error was:

Could not upgrade from version 1 to version 2: PUT info.json: The resource of this location does not exist (Exception ObjectNotFound) (404): <?xml version="1.0" encoding="UTF-8" standalone="no"?><d:error xmlns:d=“DAV:” xmlns:s=“http://ns.jianguoyun.com”><s:exception>ObjectNotFound</s:exception><s:message>The resource of this location does not exist</s:message></d:error>

Error: Could not upgrade from version 1 to version 2: PUT info.json: The resource of this location does not exist (Exception ObjectNotFound) (404): <?xml version="1.0" encoding="UTF-8" standalone="no"?><d:error xmlns:d=“DAV:” xmlns:s=“http://ns.jianguoyun.com”><s:exception>ObjectNotFound</s:exception><s:message>The resource of this location does not exist</s:message></d:error>
at newError (C:\Users\user\AppData\Local\Programs\Joplin\resources\app.asar\lib\WebDavApi.js:399:11)
at WebDavApi.exec (C:\Users\user\AppData\Local\Programs\Joplin\resources\app.asar\lib\WebDavApi.js:426:11)
at async FileApiDriverWebDav.put (C:\Users\user\AppData\Local\Programs\Joplin\resources\app.asar\lib\file-api-driver-webdav.js:201:10)
at async tryAndRepeat (C:\Users\user\AppData\Local\Programs\Joplin\resources\app.asar\lib\file-api.js:37:19)
``

Then i unistalled Joplin 1.0.242 on Device d and removed .config\Joplin & AppData\Roaming\Joplin and installed Joplin 1.0.216. Sync, and error ocurred:
Error: Sync version of the target (2) does not match sync version supported by client (1). Please upgrade your client.

Device a and Device b are still able to sync.

I don’t know how to solve it. Please help me! Thanks a lot!

Encountered same problem using JIANGUOYUN... Turns out to be me using the wrong setting in WebDAV URL.
i.e. used https://dav.xxx/dav/ instead of https://dav.xxx/dav/joplin/.