[JavaScript Error: "Component returned failure code: 0x804b000a (NS_ERROR_MALFORMED_URI) [nsIIOService.newURI]" {file: "chrome://zotero/content/xpcom/storage/webdav.js" line: 205}]

Not sure exactly what you mean, but if you're saying you get an error trying to verify a WebDAV server, 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:

https://forums.zotero.org/discussion/comment/419796/#Comment_419796