INVALID_IDEMPOTENCY_KEY
400invalid_requestThe Idempotency-Key header is missing or malformed.
Cause
Webhook write calls require the header, and the value must be printable ASCII of bounded length.
How to fix it
Send 1-255 printable ASCII characters — a UUID minted per logical request is the recommended shape.
Example response
400 INVALID_IDEMPOTENCY_KEY
JSON
{
"error_code": "INVALID_IDEMPOTENCY_KEY",
"error_type": "invalid_request",
"error_message": "The Idempotency-Key header is missing or malformed.",
"hint": "Send 1-255 printable ASCII characters — a UUID minted per logical request is the recommended shape.",
"docs_url": "https://docs.billerapi.com/errors/INVALID_IDEMPOTENCY_KEY",
"request_id": "d94f5e2a-8c3b-4f1e-9a7d-6b2c1e0f8a34"
}Related
- Error handling — the error envelope shape and how to parse it
- Error code reference — every stable error code
Canonical docs URL: https://docs.billerapi.com/errors/INVALID_IDEMPOTENCY_KEY
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