It depends whether there are any amounts in Boxes 16 and 17 (state wages and state withholding).
If those lines are blank, leave out the state code. If there are numbers, contact your organization to find out where the state wages and withholding are being reported to.
A US citizen or resident living overseas may still be a resident of the last state they lived in if they are temporarily overseas and/or did not establish a permanent residence abroad. Otherwise, you do not have to file a state return.
For most states, TurboTax will carry income information to a state return even if the state lines are blank because most states start with federal income. If your state return shows $0 income you may have to go back and add state info and change X8 to your last resident state if you need to file a state return.
Was your return accepted by the IRS @dolphingirl0057?
The IRS is still processing 2020 returns that were mailed. If your return has not been processed, the IRS has no record of your AGI. In that case use $0 for AGI.
Your return may have been adjusted. Did you get any kind of IRS letter?
You can get a free online transcript from the IRS that will show you what AGI they have on file for you.
You can get it at Welcome to Get Transcript.
If your AGI matches IRS records and you still can't file, there's an issue with their system and you will have to mail your return. Send your return by certified mail with proof of delivery so you know IRS received it.