Originally Posted by Stripe

Once you get past the page where you put in the passenger details, a PNR is created in the system. If your session gets disconnected then you're stuck. You can't book a new reservation for the same flights and you can't access the original booking to complete it. The only way to deal with it that I have found is to wait a few hours for it to fix itself, or call AA. The agent can find it and either complete the purchase for you, or cancel it so you can rebook.