HTTP status codes / 4xx — Client errors
WebDAV: the resource is locked.
The target resource is locked by another process/user (WebDAV locking). Occasionally borrowed by APIs to signal temporary edit locks.
Wait or release the lock; the response body may identify the lock owner.
The fastest way to pin down a 423 is to reproduce the exact request and inspect what actually went over the wire — status, headers, timing and body, without your app code in the way. That is what an API client is for; ReqPad does it from your phone, with every request saved to history.
400 Bad Request · 401 Unauthorized · 402 Payment Required · 403 Forbidden · 404 Not Found · 405 Method Not Allowed — or the full reference.
Build the request, send it, read status + headers + timing — on your iPhone. Free to start.