If you filed 2017 late or amended, then even if the AGI you are entering is correct, the 2017 AGI might not be in the system. You have two possible options. Try using "zero" as your 2017 AGI and see it if will let you e-file. If it will not, then you have to print, sign and mail the return.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**