Error Codes

When a payment verification fails, the AgentBureau gateway returns a 402 Payment Required or 400 Bad Request response with a specific reason string.

Payment Error Table

Reason String	HTTP	Meaning	Retry Strategy
tx_hash_already_consumed	400	This transaction hash has already been used for a successful payment.	Do not retry with the same hash. Send a new transaction.
Transaction receipt not found	402	The transaction hash is not yet visible on the Base network.	Retry after 2–5 seconds.
Transaction failed on-chain	400	The transaction was reverted on the blockchain (e.g., out of gas).	Fix the issue in your wallet and send a new transaction.
Insufficient confirmations	402	The transaction is found but hasn’t reached the required confirmation depth.	Retry after 10–30 seconds.
No valid USDC transfer found	400	The transaction succeeded but did not contain a valid USDC transfer to the GMBH wallet.	Verify recipient address and amount, then send a new transaction.
Invalid signature format	400	The PAYMENT-SIGNATURE header does not match the expected 0x-prefixed hex format.	Fix the format and retry the API call.

General HTTP Status Codes

Status	Meaning
200 OK	Request processed successfully.
400 Bad Request	Validation error (non-payment related) or malformed payment header.
402 Payment Required	Initial request (no payment) or payment verification is still pending/incomplete.
429 Too Many Requests	Rate limit exceeded.
500 Internal Server Error	Gateway or backend provider error.