What happened
The request carried no credential and the endpoint is billable. Particle Pro accepts an x402 micropayment in place of a credential, so instead of a401 the response is a 402 whose PAYMENT-REQUIRED header holds the machine-readable payment requirements (network, asset, amount, recipient). The body’s detail states the price in dollars.
The same code is returned, with a PAYMENT-RESPONSE header, when a payment was accepted but could not be settled on-chain after the request ran. The response was withheld. A payment the facilitator rejected transferred nothing; if the failure was a timeout the transfer may still have gone through, so retry the identical request with the same PAYMENT-SIGNATURE first (an authorization executes at most once) and sign a new payment only after an explicit rejection.
How to fix
1
Create an API key from the in the platform dashboard and send it on every request — see authentication.
2
Or, if your client speaks x402, fund a wallet with USDC on Base and let it pay per request — see Pay per request with x402.