The full error was:
PUT locks/exclusive_desktop_37460a5a86c54c3184070f7c64c6a1d6.json: “Joplin/locks/exclusive_desktop_37460a5a86c54c3184070f7c64c6a1d6.json” is locked (Exception OCA\DAV\Connector\Sabre\Exception\FileLocked) (423): <?xml version="1.0" encoding="utf-8"?> <d:error xmlns:d=“DAV:” xmlns:s=“http://sabredav.org/ns”> <s:exception>OCA\DAV\Connector\Sabre\Exception\FileLocked</s:exception> <s:message>“Joplin/locks/exclusive_desktop_37460a5a86c54c3184070f7c64c6a1d6.json” is locked</s:message> </d:error>
Error: PUT locks/exclusive_desktop_37460a5a86c54c3184070f7c64c6a1d6.json: “Joplin/locks/exclusive_desktop_37460a5a86c54c3184070f7c64c6a1d6.json” is locked (Exception OCA\DAV\Connector\Sabre\Exception\FileLocked) (423): <?xml version="1.0" encoding="utf-8"?>
<d:error xmlns:d=“DAV:” xmlns:s=“http://sabredav.org/ns”>
<s:exception>OCA\DAV\Connector\Sabre\Exception\FileLocked</s:exception>
<s:message>“Joplin/locks/exclusive_desktop_37460a5a86c54c3184070f7c64c6a1d6.json” is locked</s:message>
</d:error>
at newError (C:\Users\richard\AppData\Local\Programs\Joplin\resources\app.asar\lib\WebDavApi.js:399:11)
at WebDavApi.exec (C:\Users\richard\AppData\Local\Programs\Joplin\resources\app.asar\lib\WebDavApi.js:426:11)
at async FileApiDriverWebDav.put (C:\Users\richard\AppData\Local\Programs\Joplin\resources\app.asar\lib\file-api-driver-webdav.js:201:10)
at async tryAndRepeat (C:\Users\richard\AppData\Local\Programs\Joplin\resources\app.asar\lib\file-api.js:37:19)