Let me provide troubleshooting steps to get rid of the error so your customer can pay an invoice online, thegreendog2018.
You can ask the customer to open and pay the invoice using a different browser. They can select any of these browsers.
Google Chrome
Mozilla Firefox.
Microsoft Edge
Safari 11 or newer (Mac only)
If the customer can pay the invoice on a different browser, you can ask them to clear the cache and cookies on their regular browser. Follow the steps to clear the cache for your browser.
After clearing the cache, make sure to restart their browser for changes to take effect.
If they're still getting the error, they can try again to pay in an hour. If the same issue persists, I recommend contacting our QuickBooks Online Support Team.
That way, they can create a case and forward it to our Payments Team for further investigations. Here's how:
Go to the Help (?) icon.
In QB Assistant, enter the topic you need help with. You can also enter questions.
Select Contact Us to connect with a live support agent.