Why can't my clients pay by card online?

WHBMP never marks an invoice paid unless money really moved, so an invoice stays unpaid until the gateway confirms the payment.

If clients cannot pay online, check:

• The gateway is switched on under Settings > Payment Gateways, and Test Connection says it is connected.
• You are using the right kind of keys: test keys with the sandbox or test box ticked, live keys with it cleared.
• The invoice is in a currency the gateway takes (Alipay takes CNY only, PayU takes INR only, Authorize.Net bills in your merchant account's currency).
• System Logs > Payment Gateway Logs shows the gateway's own reason.
• If the client paid but the invoice is still unpaid, the gateway's webhook did not arrive. Check the webhook address and secret on the gateway's card.

You can always offer Bank Transfer with clear payment instructions and record the payment on the invoice.

See Payment gateways and recording payments and Automatic payments.