414 URI Too Long
Meaning
The URI requested by the client is longer than the server is willing or able to interpret. Often the result of too much data being put in a GET request query string.
When to Use
When the requested URL (including path and query) is excessively long, typically beyond server or application limits. This usually happens if form data is erroneously sent via GET or if there's an infinite redirect loop generating a huge URL.
Example
A client sending a very large query string (perhaps by encoding a big JSON payload into the URL) may receive 414 URI Too Long, indicating the server cannot process such a long URL.
When Not to Use
Do not use if the URL length is within acceptable limits but other issues exist. If a different problem is present (like unsupported media type), use the appropriate status code instead.
Source
RFC 9110