400 is generic bad request; 422 often means syntactically fine but semantically invalid (API-dependent).

400 only from one client?

Compare headers and body serialization between clients.

Some stacks reject bodies on GET—use POST or query params.

Error fix

How to fix “400 Bad Request”

The server cannot process the request—malformed syntax, bad JSON, or invalid parameters.

Start here first. Step 1 fixes most cases—then work down the list.

400 means the server rejected the request before business logic—usually validation, parsing, or header issues.

Invalid JSON or encoding
Truncated body, wrong Content-Type, or invalid UTF-8.
Bad query or path
Parameters fail schema validation or required fields are missing.

Fix the request shape
1. Compare your payload with API docs and fix required fields.
2. Validate JSON with a linter; set Content-Type: application/json.
3. Log server-side validation errors to see exact field failures.

Also see: 400 — browse the HTTP status hub.

400 vs 422?: 400 is generic bad request; 422 often means syntactically fine but semantically invalid (API-dependent).
400 only from one client?: Compare headers and body serialization between clients.
GET with body?: Some stacks reject bodies on GET—use POST or query params.

Still stuck? Try these related fixes next.

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Original error message

400 Bad Request