Returned when no API key is presented, the key is malformed, or it doesn’t match an active partner_api_keys record. 
{ "error": { "code": "invalid_api_key", "message": "invalid API key" } }
Fix
  • Send the key as Authorization: Bearer cpk_live_… (or X-Partner-API-Key).
  • Check you’re using the right key for the environment (cpk_live_* for production, cpk_test_* for sandbox).
  • Public widget keys (cppk_*) are not accepted on this surface.