HTTP 401 error from WebDAV server for OPTIONS request
[JavaScript Error: "xmlhttp.responseXML is null" {file: "chrome://zotero/content/xpcom/storage/webdav.js" line: 1679}]
Yes, check your WebDAV username and password. Beyond that you'll need to ask the administrator of your WebDAV server (or debug this yourself if that's you). The WebDAV server appears not to be behaving entirely correctly here.
The contents of debug output logging can help you see the specific HTTP requests that are failing.
Obviously, you can also use a different WebDAV server or switch to Zotero File Storage.
The contents of debug output logging can help you see the specific HTTP requests that are failing.
Obviously, you can also use a different WebDAV server or switch to Zotero File Storage.