---
title: "Asks for a signature nobody can build — x402 defect class transfer-method-unrecognized"
description: "Asks for a signature nobody can build (transfer-method-unrecognized), an x402 defect class: Where an accepts entry names extra.assetTransferMethod, the value is an authorization standard a published x402 client can produce — eip3009 (TransferWithAuthorization), permit2, or erc7710. Detectable by an unpaid probe. A buyer who reads the field has nothing to construct from it and a buyer who ignores it signs blind. The refusal lands before any payment reaches the seller, whose logs record it as nobody wanting the goods. Absence of the field is not this class: it is optional, most doors omit it, and eip3009 is the settled default."
canonical: "https://scvd.store/defects/transfer-method-unrecognized"
url: "https://scvd.store/defects/transfer-method-unrecognized"
term_code: "transfer-method-unrecognized"
defined_in: "https://scvd.store/defects"
data: "https://scvd.store/defects.json"
vocabulary_version: "22"
license: "https://creativecommons.org/licenses/by/4.0/"
---

# Asks for a signature nobody can build

`transfer-method-unrecognized` — an x402 defect class.

**Asserts:** Where an accepts entry names extra.assetTransferMethod, the value is an authorization standard a published x402 client can produce — eip3009 (TransferWithAuthorization), permit2, or erc7710.

**Costs:** A buyer who reads the field has nothing to construct from it and a buyer who ignores it signs blind. The refusal lands before any payment reaches the seller, whose logs record it as nobody wanting the goods. Absence of the field is not this class: it is optional, most doors omit it, and eip3009 is the settled default.

**Detectable:** unpaid — a free probe can see it

**Falsified by:** The same entry naming one of the published methods at the stated moment, or a client implementation that builds an authorization from the named method — the second retires the finding by making the method recognized, and the register is the thing that should move.

**How an operator clears it:** Name the method your facilitator actually verifies — for USDC on an EVM rail that is almost always eip3009 — or omit the field, which reads as eip3009 by default. If the value names a standard your own stack defines, publishing what a client must build for it turns a door only your clients can walk into one anybody can.

**What a buyer does:** Do not sign blind. If the named method is one your client can build, build it; if not, refuse, because a signature over the wrong authorization standard is money sent under terms neither side agreed to. Absence of the field is not this class and reads as eip3009.

**Our signal:** `transfer-method-signable`

---

Vocabulary v22, CC BY 4.0. Every class: https://scvd.store/defects. Machine-readable, with falsifiers and cross-instrument mappings: https://scvd.store/defects.json.

A class describes a property of one endpoint at one moment and never accumulates into a judgment on an operator.