# gateway.payment_method.card_invalid_number

> For the complete machine-readable documentation index, see [llms.txt](https://apidocs.chargebee.com/llms.txt).


**gateway**

The card number is invalid. This can happen when the customer enters an incorrect, incomplete, or improperly formatted card number, uses an unsupported card type, or submits a test or placeholder number.

## Recommended Customer Message

Your transaction could not be completed because the card number you entered is invalid. Please re-verify the card number and try again. If the issue persists, consider using a different payment method or contact your bank for assistance.

## Root Cause[](#root-cause)

-   **Incorrect card number:** The customer mistyped or entered an incomplete card number.
-   **Invalid card format:** The provided number does not meet the required format or fails validation checks such as the Luhn algorithm.
-   **Unsupported card type:** The entered card number belongs to a card type not supported by the payment gateway.
-   **Test or placeholder number:** A dummy or test card number was mistakenly used in a live transaction environment.

## Troubleshooting and Solutions[](#troubleshooting-and-solutions)

-   Ask the customer to carefully re-verify and enter the correct card number.
-   Ensure the card number matches the expected format and length for the card type being used.
-   Recommend using a different payment card if the issue persists.
-   Suggest contacting the bank if the customer continues to experience difficulties with the valid card number.
-   Implement real-time validation on the payment form to help prevent incorrect or invalid card number submissions.