I've had the exact same thing happen. I file my parent's tax returns and my dad passed away in 2019. Tried yesterday to submit my Mom's (married filing jointly) return three times and all three times I got the error message: IND-031-04 The primary taxpayer's AGI or self-select PIN from last year does not match IRS records. The 2018 AGI in Turbo Tax is correct. I have always filed their returns electronically using Turbo Tax so I'm not sure how the IRS could have a different 2018 AGI than what I have in Turbo Tax that was submitted to the IRS last year. Seems to me that maybe what is being passed from Turbo Tax to the federal government (during the eFiling process) is maybe missing one or more fields for the deceased taxpayer. As you go through the review steps prior to submitting, never does Turbo Tax ask for the self-select PIN of the deceased person - just the surviving spouse. I checked the underlying worksheet in Turbo Tax and made sure the prior year PIN numbers are there and they are. With a number of people encountering the same problem, I'm hoping Turbo Tax will take a look to see if there is a programming problem. This is very frustrating.
