23.09.2026-1
A device’s key is required everywhere: when you register the device and on every ad request. The ad request already listed it as required, while the device resource called it optional.
Register every device with a key
Section titled “Register every device with a key”devices:upsert without a non-empty identifier.key is rejected with INVALID_ARGUMENT, so every device’s externalId is "{key}_{playerId}".
Send key on every ad request
Section titled “Send key on every ad request”GET /v1alpha2/ads requires key together with playerid, the same pair the device was registered with. Send both on every request.
What to do
Section titled “What to do”Nothing, if every device you registered has a key and your players send it. A device registered without a key cannot be given one, because its identity is fixed when it is created. Delete it, register it again with a key, and have its player send that key.