I had the same error and waited a few days.
Today, I deleted all answers and completed the form.
The return was accepted right after a re-submitted.
The only change I made was instead a just "MO" for state, it pre populated "MO - Missouri".
I don't know if that held up the return, but it's worth a try. They let you e-file up to 5 times before it has to be mailed. Good luck!
