@Mehdimho You're posting in a 3-year-old thread that transferred into this new forum when it started a few weeks ago. All old threads were given an early June 2019 date when they were transferred unfortunately.
In regard to using a 2017 AGI to efile your 2018 return, be sure you are using the AGI from the original 2017 return, not an amended one.
If it's a joint return, use the same total AGI for both spouses. Do not divide it.
If you filed your 2017 return real late in the year, such as November 2018 or later, then try an AGI of 0 (zero.)
If you want, you can download a 2017 tax return transcript at the IRS website, to see what they show for your 2017 AGI.
http://www.irs.gov/Individuals/Get-Transcript
NOTE: If nothing works, then before you give up and file by printing and mailing, try using an AGI of 0 (zero) sort of like a "Hail Mary" football pass. Even though I can't explain it, it worked for some people.
Also see this:
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/00/25947
and
https://ttlc.intuit.com/community/rejections/help/what-if-i-entered-the-correct-agi-and-i-m-still-ge...
