400 Bad Request
The server will not process the request because of something the client got wrong, such as malformed syntax.
What to do
Something in the request is malformed. Check the body parses, the Content-Type header matches it, and the URL is properly encoded. The response body often says what the server could not read.
- Class
- 4xx Client Error. The request has a fault, or cannot be met as sent.
- Registered
- Yes, in the IANA HTTP status code registry.
- Cacheable by default
- No. A cache stores it only when Cache-Control or Expires says to.
- References
- RFC 9110 ยง15.5.1 · MDN
Every 4xx code
- 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 (Unused)
- 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
- 444 (No name)
- 451 Unavailable For Legal Reasons
- 460 (No name)
- 463 (No name)
- 464 (No name)
- 494 Request Header Or Cookie Too Large
- 495 SSL Certificate Error
- 496 No Required SSL Certificate Was Sent
- 497 Plain HTTP Request Sent to HTTPS Port
- 499 Client Closed Request