Look for an ACTION NEEDED! email from turbotax@intuit.com. It will give you a brief explanation of your reject and how to update it.
Didn't get an email? Open your return to get the rejection reason and proceed to step 2.
How to fix a rejected return:
https://ttlc.intuit.com/replies/3302275
Here is information about returns that keep getting rejected, although all of the information is correct:
https://ttlc.intuit.com/replies/3302281