Are there non-alphanumeric characters in your WebDAV URL, username, or password?
See this thread for how you can experiment to see what characters are causing this error, and please return to this thread and let us know the results:
@banjgaiscuarwjk: Can you explain exactly what you did? We get a huge number of reports of this, and no one has ever come back and explained what they did to fix it or what was causing it in the first place.
Actually, I think you are right, there are some problems in my WebDAV URL, username, or password, but I didn't find out. Just now, I inputted my WebDAV URL, username, or password carefully again, then I succeed.
But do you know what exactly you entered to trigger the error in the first place? We've been trying to figure out how to even reproduce this for a very long time.
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See this thread for how you can experiment to see what characters are causing this error, and please return to this thread and let us know the results:
https://forums.zotero.org/discussion/comment/419796/#Comment_419796