I keep getting an error message "oops" when I try to submit my final and pay. What should I do next?

I had the same problem. I deactivated my VPN to get to the Turbotax payment page. Then reactivated the VPN. It worked fine after that. (If that doesn't work, also check whether popups are enabled/disabled.)

Please try the steps in the below TurboTax help article to see if it helps resolve the issue. 

Why am I stuck in a loop in the File section of my return?