Summary
The server cannot process the request due to a client error such as malformed syntax.
When it occurs
Returned when the request is malformed, has invalid framing, or fails basic validation.
Common causes
- Malformed JSON or request body
- Invalid or missing query parameters
- Wrong Content-Type for the payload
- Oversized or corrupted cookies/headers
How to fix
- Validate the request syntax and body
- Check the Content-Type header matches the payload
- Inspect and fix query parameters
- Clear cookies if headers are corrupted