Already filed and now I was notified there were critical updates to 1040 form. What am I supposed to do now?

Do the updates in your program, and then open and look at your 1040 return, and if the tax is the same and it shows no errors, then do nothing.

Critical updates can be just Forms being finalized and you might not even needed to use any of those forms.

If there are changes to your taxes (refund or balance due) then wait for your return to be fully processed by IRS and you get your refund.  Then Amend the return.

5-1-2020:  I filed on tax day, April 15.  Today I wanted to take a look at the filing and opened Turbo Tax.  I got the Critical Updates notice.  1.  It's a shame that Intuit reps don't answer questions in this forum, seems to be only other users wishing to help others.  2.  Why does Turbo tax think it's an acceptable practice to roll out critical updates after filing, resulting in amendments, at best?  3.  The recommendation to save a PDF first would not work for me because Turbo Tax wouldn't let me open Turbo Tax without updating first.  Luckily I had already saved PDF of the filing earlier.  I cancelled the update and and used the PDF for my review.  Wondering why I didn't just use the PDF to begin with...I simply forgot I had saved it.  Anyway, sub-par way to run a business that provides software that must be perfect to satisfy our government overlords.