# Seller never delivers: `/t/always-402`

> A valid quote, but every paid retry is answered with another 402 and a failed settlement. A free public x402 test endpoint: Stop after a small, fixed number of retries and report the failure. Do not loop.

|  |  |
| --- | --- |
| Endpoint | `GET https://x402testendpoint.com/t/always-402` |
| Kind | trap: a correct buyer does not pay |
| Payment scheme | `exact` |
| Quoted price | $0.001 in test USDC |
| Networks | Base Sepolia (testnet) (default), Solana Devnet (testnet) |
| Cost to you | Nothing. Test USDC has no value. |

## What the seller does

A valid quote, but every paid retry is answered with another 402 and a failed settlement.

## What a correct buyer does

Stop after a small, fixed number of retries and report the failure. Do not loop.

## Why test this

If a seller keeps answering 402, a client that retries without a limit signs a new payment every time. With a seller that settles each one, that is an unbounded loss.

## Run it

See the quote without paying:

```bash
curl -i https://x402testendpoint.com/t/always-402
```

Then point your own client at it, or use the official one:

```ts
import { x402Client, x402HTTPClient } from "@x402/core/client";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.BUYER_KEY);
const core = new x402Client().register("eip155:84532", new ExactEvmScheme(account));
const http = new x402HTTPClient(core);

const first = await fetch("https://x402testendpoint.com/t/always-402");
const quote = http.getPaymentRequiredResponse((h) => first.headers.get(h));
const headers = http.encodePaymentSignatureHeader(await core.createPaymentPayload(quote));
const paid = await fetch(first.url, { headers });
console.log(paid.status, paid.headers.get("x-test-verdict"));
```

The wallet needs test USDC on Base Sepolia (testnet) for scenarios that settle. Circle's faucet at https://faucet.circle.com provides it.

## Other networks

Add a `network` parameter to run the same scenario elsewhere:

| Network | URL | Notes |
| --- | --- | --- |
| Solana Devnet (testnet) | `https://x402testendpoint.com/t/always-402?network=solana-devnet` | Test USDC on Solana Devnet. Register `ExactSvmScheme` from `@x402/svm/exact/client`. |

Traps run on test networks only. A signed mainnet payment is spendable by whoever holds it until it expires, so this site does not invite one for a seller built to misbehave.

## What you will see

This is a trap: there is no successful payment. A correct client stops without sending a `PAYMENT-SIGNATURE` header, or stops retrying, and reports the problem to its caller.

If your client pays what it should have refused, the endpoint answers HTTP 400 with `x-test-verdict: fail` and a `reason` in the JSON body. The payment is not verified, settled, stored or logged, so no funds move.

## How the official client behaves

`@x402/core` 2.31 with default settings: The core client only builds payments; nothing in it limits how many times it is asked to sign, so the calling code or wrapper must stop.

## Related errors

- [`invalid_exact_evm_transaction_failed`](https://x402testendpoint.com/errors/invalid_exact_evm_transaction_failed): The payment passed verification but the on-chain transfer failed.

## Other scenarios

- [Standard payment](https://x402testendpoint.com/scenarios/ok) (pay)
- [Pick the supported option](https://x402testendpoint.com/scenarios/choose) (pay)
- [Slow seller](https://x402testendpoint.com/scenarios/slow) (pay)
- [Pay up to a maximum](https://x402testendpoint.com/scenarios/upto) (pay)
- [Absurd price](https://x402testendpoint.com/scenarios/overpriced) (trap)
- [Price changes after you pay](https://x402testendpoint.com/scenarios/price-bump) (trap)
- [Unsupported network only](https://x402testendpoint.com/scenarios/wrong-network) (trap)
- [Unreadable quote](https://x402testendpoint.com/scenarios/malformed) (trap)
- [Quote without a recipient](https://x402testendpoint.com/scenarios/missing-fields) (trap)

Source: https://x402testendpoint.com/scenarios/always-402