is asking for the AGI for 2023. I filed form 1040-SR and the line for AGI is blank. Where do I find that figure?

The  AGI line on your 2023 return is blank?  Are you looking in the right spot?  You need your 2023 AGI to efile 2024. The AGI is on 2023 1040 or 1040SR line 11. If you filed a Joint return you use the same AGI for each spouse.

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

If you didn't file 2023 or filed it later in the year or mailed it, then try entering 0 for the AGI. If that doesn't work you will have to print and mail your return.

Or request a transcript from the IRS
https://www.irs.gov/individuals/get-transcript

Using 0.00 worked and fed and state returns were accepted. Thank you