First, note that you're running a version of Zotero from last December. You should install the latest version from the download page and figure out why you haven't received automatic updates for many months.
您的 WebDAV 服务器对 GET 请求返回了 HTTP 401 错误。
如果您频繁收到此消息，请检查您的 WebDAV 服务器设置，或联系 WebDAV 服务器的管理员。
For file syncing, you're getting a 401 Unauthorized error from your WebDAV server. I'm afraid that's all we can tell you.
(Note that files that were available on a given computer wouldn't become unavailable, but this would prevent you from being able to open files you'd added elsewhere.)
Upgrade Storage
(Note that files that were available on a given computer wouldn't become unavailable, but this would prevent you from being able to open files you'd added elsewhere.)