← Reason code checker

Amex P01: Unassigned Card Number

What it means: The issuer says the card number used was not valid / not on file, or did not match the account.

How to respond: Provide the authorization record showing the transaction was approved for that card number. These codes are usually processing issues; check the payment details with your processor.

Stripe usually labels this dispute as: general (check the reason shown on your dispute — Stripe maps network codes to its own categories).

Evidence checklist

• Authorization record for the transaction (authorization code, date, amount) from the payment details
• Receipt / invoice showing what was purchased, price, date and the customer's details

Tips

• Address the specific reason code — a generic letter that argues the wrong issue is a common reason responses fail.
• Submit before the evidence due date shown in your Stripe/Shopify dashboard; most processors allow one submission.
• Keep it factual and concise; label each exhibit.
• If the customer is right, accepting the dispute or refunding may cost less than fighting it.

DisputeDesk provides general information and document preparation help. It is not legal advice, and we do not guarantee any dispute outcome — the card issuer decides. Reason-code names and rules change; always check the dispute details in your Stripe or Shopify dashboard and the card network's current rules.
DisputeDesk is operated by Avenbridge Technology Limited (Hong Kong). Privacy