Good day, KSWEISS.

Thanks for joining us here. Let me share additional details on how we can fix this. 

You'll want to clear the cache since it worked in the incognito window. It's a junk file that can cause errors in QuickBooks Online.

Also, make sure that the browser you're using when paying the invoice is updated or use a different one. I suggest Google Chrome, Mozilla Firefox, or Microsoft Edge.

If this error continues, please reach out to our Customer Support Team for further investigation.

1. Go to Help and select Contact us.
2. Enter the error message and click Let's talk.
3. Choose either Start messaging or Get a callback.

Here are some of the articles you'll want to check for more details:

• Take and process payments in QuickBooks Online
• QuickBooks Payments FAQs

I'll be here if you need anything else. Stay safe!