Payment Unverifiable¶

Type URI: https://usp-protocol.dev/errors/payment-unverifiable

A POST /bookings/{booking_id}/confirm-payment call could not be verified, because the business has no price to check the payment against. For example, the booking's service no longer exists, or a payable service states no price. Returned with 409 Conflict.

The booking is not confirmed. A platform must not report it to the buyer as confirmed. It should reverse or refund the payment through the checkout system that collected it, and should not retry the same request unchanged.

This is not payment_amount_mismatch. That business outcome applies when the business has a price and the payment disagrees with it, and it is carried as a messages[] entry with HTTP 200 OK.

Over MCP, the same condition is JSON-RPC -32002 with data.code payment_unverifiable.

Servers use this URI as the type member of an RFC 9457 Problem Details response. Clients must branch on the exact URI, not the human-readable title.