https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947

To access your current or prior year tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show.  Click on the Year and Click on View adjusted gross income (AGI)

Or go to this IRS website for free federal tax return transcripts - https://www.irs.gov/individuals/get-transcript

If your tax return continues to be rejected with the 2018 AGI then enter a 0 (zero) for the AGI and e-file again.

If this is also rejected then you will have to print and mail the tax return.

See this TurboTax support FAQ for printing a tax return for mailing - https://ttlc.intuit.com/community/printing/help/how-do-i-print-and-mail-my-return-in-turbotax-online...

Hello. You can visit www.irs.gov. From home page, click on "view my account". You can then sign up for account access and retrieve your free tax return transcript that will show your AGI.  If you have problems signing up for an account, you can request a transcript using the automated telephone system by calling [phone number removed]. If you have moved and updated your address with the U.S. Postal Service, it will be forwarded and the IRS will usually automatically update your address unless you have prior ID Theft problems. If you didn't do address update with postal service, it will go to an incorrect address. You can complete and submit Form 8822 and mail to the IRS if you need to do an address change.