If you are attempting to file for 2020 tax year, which given the date of your submission I think that you are, the IRS is not beginning the processing of returns until February 12th 2021 for 2020 tax year. Therefore, should you have received a rejection message please make sure you are in the correct program year.
Having said that to start, it appears as though you might have accidentally joined a "thread" that might be almost completely unrelated to your direct error message in that you have been filing separate or single since 1982. The next step I would suggest you take is that you request a transcript from the IRS for your 2019 Personal Income Tax Return. You can do this easily and with rather almost instantaneous results by going to the following link and follow the instructions provided by the IRS:
Get Transcript | Internal Revenue Service (irs.gov)
This will show you what your accepted information was for the prior year, including the AGI they have on file for you.
