TL;DR: A bank-redirect method like iDEAL was submitted without an issuer. Render the issuer list from /paymentMethods, require the shopper to pick a bank, and forward the issuer id unchanged.

The exact error:

```text
14_020 - No issuer selected
```

## The fix

1. Render the issuer options from the /paymentMethods response instead of hardcoding them.
   Expected: Your checkout shows the current bank list.
2. Require an issuer selection before submit and forward the issuer id unchanged.
   Expected: The request always carries the shopper's choice.
3. For returning shoppers, store the issuer with the token and include it on repeat payments.
   Expected: The shopper is redirected to their bank.

## When this applies

- iDEAL or similar payments return 14_020
- You built a custom bank-select screen
- Repeat payments with stored redirect details fail

## When it does NOT apply

- Card payments (no issuer concept)
- Wallet payments like PayPal
- The issuer is present but the bank rejects the shopper (a different, later error)

## Versions

Adyen Checkout API v68 through v71. Applies to issuer-based redirect methods.

## Why it happens

Redirect methods route the shopper to a specific bank. Without an issuer Adyen does not know where to redirect, so the request fails validation.

## Edge cases and pitfalls

- The issuer list comes from /paymentMethods; hardcoding issuers breaks when banks change
- Some issuers are test-only and fail in live with a different error
- If the shopper skips the bank select screen, your frontend must still send a default or re-prompt