My client is trying to pay through the emailed invoice but keeps getting an error code when they click pay by debit card button.

Hi usercraig_mcinnes,

Thank you for raising your client's concern. Let's check to see why they can't proceed with their payment. 

First of all, what is the error? When you send the invoice to your email and pay it, do you get the same error? If not, they could just be experiencing browser issues, and they can follow the steps below.

They can sign in to QuickBooks using a private browser. This step disables the extensions and stops the cache from saving their browsing history.
 

• Google Chrome: Ctrl + Shift + N
• MS Edge and Firefox: Ctrl + Shift + P
• Safari: Command + Shift + N

If there's no error when browsing privately, they can go back to their regular browser and clear the cache. If not, please try other browsers to see if they get the same thing.

Let me know how it goes or if you have other concerns about the invoice payment processes. Take care and good evening!

Thank you for getting back to me, I’ve tried sending it to my self and I get the same thing, it says “Error, you can try again, or come back later and try connecting then.” I tried using private browser as well and got the same error.

Hello there, @usercraig_mcinnes

.I can route you to the right person who'll take care of this for you.

If you're still having problems after trying all of the suggested solutions, I recommend contacting Customer Support. Rest assured that they will investigate this further and provide you with the best possible response to your problem.

To contact support:

1. Log in to your QuickBooks Online company.
2. Click on Help (?).
3. Choose between Talking to a Human or Chat.

Please note their support hours to ensure they're available for assistance.

I'm gonna add this article so you'll learn more on how to handle sales forms in QBO: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Feel free to comment back for more help. We're here to assist anytime. Take the best care!