unauthorized

A valid API key is required.

What it means: An Authorization header was present and did not carry a valid key. The free tier needs no key: omit the header entirely to use it.
What to do: Check the key, or drop the Authorization header for free-tier access.
Retry: Fix the request; do not retry as sent.
Who changes what: The caller. The request as sent cannot be answered; the detail field says why.
On the wire: Content-Type: application/problem+json
{"type":"https://www.veridionmarkets.com/data-api/problems/unauthorized","code":"unauthorized","status":401,…,"request_id":"…"}

Documented for version 1.3.5. The request_id in the body equals the X-Request-ID header; quote it to support@veridionmarkets.com. All problems · API page