`invalid_exact_evm_signature`

The signature does not match the transfer authorization for this token and chain.


Reported by	the facilitator, during verify
Usually fixed by	the buyer or the seller, depending on the cause

Cause

The facilitator rebuilds the EIP-712 TransferWithAuthorization data from the quote (token name and version from extra, chain id, token address) and the payload's authorization fields, then checks the signature against the payer. Any difference between what the buyer signed and what the facilitator rebuilds fails here.

Fix

Buyer: sign with the name and version given in the quote's extra, not hard-coded values. USDC is named USD Coin on Base and USDC on Base Sepolia.
Buyer: check the chain id and the token address used as verifyingContract match the quote.
Buyer: the signer must be the address in authorization.from.
Seller: check that extra.name and extra.version are the token's real values. See token name mismatch.

About this reference

Causes are taken from the source of @x402/evm 2.31. Other facilitators and later versions may use the same code for slightly different checks. See all x402 errors.