# Adyen: Invalid card number (error 101)

**TL;DR:** The card number failed basic validation: wrong length, non-numeric characters, or a failed Luhn check. Strip spaces, confirm it is all digits, and re-collect it through Adyen's secured card component instead of hand-rolled inputs.

```text
101 - Invalid card number
```

## Steps

1. **Sanitize the input.** Remove spaces and dashes, then confirm the result is digits only. A single stray character is enough to trigger 101.
   - *Success check:* the cleaned value matches the digits the shopper typed.
2. **Check the length against the brand.** Most brands are 16 digits, Amex is 15. Anything outside the brand's valid lengths fails.
   - *Success check:* digit count matches the detected brand.
3. **Run a Luhn check client-side.** It catches typos before the number ever reaches Adyen.
   - *Success check:* the number passes Luhn before you call /payments.
4. **Use the secured card component.** Adyen's Card component and client-side encryption handle formatting, brand detection and encryption for you. Raw card numbers posted by custom forms are the main source of 101s.
   - *Success check:* the payment request carries encrypted card data and 101 stops appearing.

## When to use this

- /payments returns 101 on card payments.
- Shoppers report "card declined" but your logs show 101, which is a validation failure, not a decline.

## When NOT to use this

- Error 102 (unable to determine variant). That means the BIN is unknown, not that the number is malformed.
- A real decline (resultCode Refused). That is the issuer saying no, not a formatting problem.

## Compatibility

Adyen Checkout API card payments, Web Drop-in/Components and API-only integrations.

## Why it happens

101 is Adyen telling you the number itself is malformed: typo, pasted with spaces, truncated by a maxlength on your input, or a test card number used in the wrong environment. It can also surface from 3DS flows when PaRes comes back with wrong capitalization.

## Edge cases

- Test card numbers only work in TEST. Using one against LIVE gives confusing failures.
- If your own input masks the number (maxlength 16), Amex cards (15 digits) still work but 19-digit cards get truncated. Prefer the Adyen component.