HTTP status codes / 4xx — Client errors
The URL itself exceeds server limits.
Usually the result of stuffing data into query strings (filters, ID lists, redirect loops appending parameters). Limits are commonly around 4-8KB at proxies and servers.
Move the data into a POST body, or check for a redirect loop that keeps growing the query string.
Server-side note: Move data into a POST body, or break the redirect loop. Proxy limits sit around 4-8KB.
The fastest way to pin down a 414 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.