How did you file in 2020?  If you filed as Married Filing Joint & are filing the same this year, then us the same 2020 AGI for both of you.

If you filed as Married Filing Separate in 2020 & are filing Married Filing Separate this year, then you need to enter your own 2020 AGI from your separate returns, on each of your own returns.  If you are going from Married File Separate to Married Filing Joint, you still would enter each of your 2020 AGI from each 2020 return.

If all else fails, try using a zero.  Also, see the following:

What if I entered the correct AGI and I'm still getting an e-file reject?

https://ttlc.intuit.com/community/rejections/help/what-if-i-entered-the-correct-agi-and-i-m-still-ge...