Most checkout errors come from the payment processor or the registrant's bank, not from Certain. The message usually tells you who can fix it.

Common errors

• PayPal "10002 Security header is not valid": the PayPal API credentials saved in Certain are wrong or were changed in PayPal. Update them in your event's payment settings. See Administrators - PayPal Setup Requirements
• Pay.gov "3001" or another Pay.gov response code: the card was declined by the bank or by Pay.gov. The registrant should contact their bank or Pay.gov. See Pay.gov - Response 4054
• Address verification (AVS) failures: the billing address doesn't match what the bank has on file. Ask the registrant to enter the address exactly as their bank has it. If many cards fail the address check, look at the address settings on your processing account. Go to Account Settings > Registration > Financial Data and open the account under E-commerce Accounts. The options are Collect Billing Address, Match Zip Code, Match Street Number and Require AVS "Yes" Response. Only an Administrator can change them there. Each event also has these options, under Plan > Event Setup > Financials in Online Payment Security Options, the same page where you pick the event's processing account. Check both.
  
• "Enter Amount is not valid": the registration usually has nothing left to pay. Check the registration's Financials page. If a payment already went through, the balance is $0.00.

Charged, but saw an error?

Open the registration and go to Financials. A payment can be listed under Payments even if it didn't go through, because failed attempts can show there too. Look at the Received column:

• A check mark under Received means the payment was processed successfully.
• No check mark means the payment wasn't received. Don't count it as paid.

Also check the Balance. If the payment went through, the balance goes down by that amount. If there's no received payment, check your processor's dashboard for the charge before you ask the registrant to pay again.

Who to contact

• The registrant's bank: declined cards and address mismatches on one card.
• Your payment processor (PayPal, Stripe, Pay.gov and others): account, credential and settlement questions.
• Certain Support: the same error for many registrants, or a charge in your processor that doesn't show in Certain.

Next step: Check the registration's Financials page, then match the error to the list above.