4xx Client Error
HTTP 400 Bad Request
The server cannot process the request because it is malformed.
Check a URL's HTTP statusWhat 400 means
Common causes are invalid JSON, a malformed URL, missing required fields, or headers that are too large or corrupted.
Common causes
- Invalid JSON or form data in the request body.
- A corrupted or oversized cookie.
- Invalid characters in the URL.
How to fix it
- Validate the request body and query parameters.
- Clear the site's cookies and try again.
- Check the API documentation for required fields.
How to check a status code
Enter a URL in the HTTP Status Checker to see its status code, every redirect hop, and response time. For redirect-heavy pages, the Website Speed Test shows how much time redirects add.
FAQ
- What does HTTP 400 mean?
- 400 Bad Request is a 4xx client error status code. The server cannot process the request because it is malformed.
- What causes a 400 error?
- Invalid JSON or form data in the request body. A corrupted or oversized cookie. Invalid characters in the URL.
- How do I fix HTTP 400?
- Validate the request body and query parameters. Clear the site's cookies and try again. Check the API documentation for required fields.
Defined in RFC 9110.
Other 4xx client error codes
401 Unauthorized403 Forbidden404 Not Found405 Method Not Allowed406 Not Acceptable408 Request Timeout409 Conflict410 Gone413 Content Too Large414 URI Too Long415 Unsupported Media Type418 I'm a teapot422 Unprocessable Content425 Too Early429 Too Many Requests431 Request Header Fields Too Large451 Unavailable For Legal Reasons