HTTP 400 Bad Request

What is HTTP 400 Bad Request?

The 400 (Bad Request) status code indicates that the server cannot or will not process the request due to something perceived as a client error — malformed request syntax, invalid request message framing, or deceptive request routing. This is a generic client error response that should be accompanied by an error message explaining the specific problem.

Common Use Cases

• Malformed JSON or XML in API requests
• Invalid query parameters
• Missing required headers
• Request body parsing errors

// Laravel - returning 400 for malformed JSON
try {
    $data = json_decode($request->getContent(), true, 512, JSON_THROW_ON_ERROR);
} catch (\JsonException $e) {
    return response()->json([
        'error' => 'Invalid JSON',
        'message' => $e->getMessage(),
    ], 400);
}