# `invalid_exact_evm_nonce_already_used`

> This exact payment authorization has already been spent or cancelled. What causes this x402 error and how to fix it.

This exact payment authorization has already been spent or cancelled.

|  |  |
| --- | --- |
| Reported by | the facilitator, during verify |
| Usually fixed by | the buyer |

## Cause

The token contract reports the authorization's nonce as used for this payer. Each authorization can be settled once.

## Fix

- Buyer: generate a new random nonce and sign again for every attempt. Do not resend a payment header that already settled.
- If you retried after a timeout, the first attempt may have settled. Check the payer's transactions before paying again.

## 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](https://x402testendpoint.com/errors).

Source: https://x402testendpoint.com/errors/invalid_exact_evm_nonce_already_used