Are you looking at the right line? It should at least be zero. AGI is on 2019 line 8b. Try entering 0 for the AGI.
Enter 0 (zero) as your AGI.
The IRS requires your AGI from last year so that it can verify your identity in the electronic filing process.
I checked 8b and it was blank. I had put 0 as the AGI and my return had gotten rejected