API error · HTTP 400

`invalid_json`

Request body is not valid JSON

HTTP status	400 Bad Request
`code`	`invalid_json`
`title`	Request body is not valid JSON
Retry?	No

What it means

The request body could not be parsed as JSON.

What to do

Do not retry unchanged. Serialise the body with a JSON library (UTF-8) and send it with Content-Type: application/json (§5).

Example response

Branch on code, never on title or detail. detail varies; quote request_id to support.

HTTP

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json

{
  "type": "https://www.underwritinguk.ai/developers/errors/invalid_json",
  "title": "Request body is not valid JSON",
  "status": 400,
  "code": "invalid_json",
  "detail": "Request body is not valid JSON.",
  "request_id": "7b0b1e5c-2f7e-4a52-9a43-5b0d0f0e9d11"
}

All error codes · Error catalogue in the integration guide (§15) · Error handling and retries (§12.4)