# `invalid_exact_evm_authorization_value`

> The signed amount is not exactly the quoted amount. What causes this x402 error and how to fix it.

The signed amount is not exactly the quoted amount.

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

## Cause

In the `exact` scheme the authorization `value` must equal the required amount in atomic units. Paying more or less both fail.

## Fix

- Buyer: sign for the quote's `amount` exactly, as an atomic-unit string. For USDC, `1000` is 0.001 USDC.
- Seller: do not change the price between quoting and verifying. The [price-bump scenario](https://x402testendpoint.com/scenarios/price-bump) shows what a buyer sees when a seller does.

## Reproduce it

The [Price changes after you pay scenario](https://x402testendpoint.com/scenarios/price-bump) on this site exercises this situation.

## 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_authorization_value