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