Here are all the codes we support (and any special notes):
100 - Continue
101 - Switching Protocols
102 - Processing
103 - Early Hints
200 - OK
201 - Created
202 - Accepted
203 - Non-Authoritative Information
204 - No Content
205 - Reset Content
206 - Partial Content
207 - Multi-Status
208 - Already Reported
226 - IM Used
300 - Multiple Choices
301 - Moved Permanently
302 - Found
303 - See Other
304 - Not Modified
305 - Use Proxy
307 - Temporary Redirect
308 - Permanent Redirect
400 - Bad Request
401 - Unauthorized
402 - Payment Required
403 - Forbidden
404 - Not Found
405 - Method Not Allowed
406 - Not Acceptable
407 - Proxy Authentication Required
408 - Request Timeout
409 - Conflict
410 - Gone
411 - Length Required
412 - Precondition Failed
413 - Content Too Large
414 - URI Too Long
415 - Unsupported Media Type
416 - Range Not Satisfiable
417 - Expectation Failed
418 - I'm a teapot
421 - Misdirected Request
422 - Unprocessable Content
423 - Locked
424 - Failed Dependency
425 - Too Early
426 - Upgrade Required
428 - Precondition Required
429 - Too Many Requests
431 - Request Header Fields Too Large
451 - Unavailable For Legal Reasons
500 - Internal Server Error
501 - Not Implemented
502 - Bad Gateway
503 - Service Unavailable
504 - Gateway Timeout
505 - HTTP Version Not Supported
506 - Variant Also Negotiates
507 - Insufficient Storage
508 - Loop Detected
510 - Not Extended
511 - Network Authentication Required
520 - Web Server Returned an Unknown Error (non-standard status code)
521 - Web Server Is Down (non-standard status code)
522 - Connection Timed out (non-standard status code)
523 - Origin Is Unreachable (non-standard status code)
524 - A Timeout Occurred (non-standard status code)
525 - SSL Handshake Failed (non-standard status code)
526 - Invalid SSL Certificate (non-standard status code)
527 - Railgun Error (non-standard status code)
530 - Origin DNS Error (non-standard status code)