What is HTTP 400 Bad Request?
The 400 Bad Request status code indicates that the server cannot understand or process a request because the request is invalid.
It belongs to the 4xx Client Error category, meaning the problem is usually caused by the client sending an incorrect request.
Common Causes
- Malformed JSON payloads
- Invalid query parameters
- Incorrect request formatting
- Invalid cookies or headers
- Unsupported request data
Example
HTTP/1.1 400 Bad RequestWhy Does It Matter For DevOps?
DevOps engineers commonly encounter 400 errors when debugging APIs, reverse proxies, and application integrations.
- Checking application logs
- Validating API payloads
- Debugging client integrations
Summary
400 Bad Request means the server received a request it could not process because the request itself was invalid.