The knowledge combined here comes from RFCs, mailing lists, bug reports, code repositories, Q&A forums, hard-won life experiences, and personal judgments (as opposed to copying and pasting RFCs without any value add).
These status codes indicate the request was successfully understood and accepted by the server.
These status codes indicate the client should take an additional step to complete the request.
Client errors (4xx)
These status codes are reserved for cases when the error is caused by the client.
- HTTP 405 - Method Not Allowed
- HTTP 410 - Gone
- HTTP 411 - Length Required
- HTTP 413 - Request Entity Too Large
- HTTP 414 - Request URI Too Long
- HTTP 415 - Unsupported Media Type
- HTTP 416 - Range Not Satisfiable
- HTTP 426 - Upgrade Required
- HTTP 429 - Too Many Requests
- HTTP 431 - Request Header Fields Too Large
Server errors (5xx)
These status codes are reserved for cases when the problem originates from the server.