Proof Nonce Required¶

Type URI: https://usp-protocol.dev/errors/proof-nonce-required

The business requires a nonce in the proof of possession. The response carries the nonce; the client retries with a freshly built proof that includes it.

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.