Hello @SolaB1207,
Being able to make your payments can be very important if it is your main form of paying your bill. I will be happy to offer some troubleshooting options!
If you are receiving an error while trying to pay through the app, you will want to make sure you have an active internet connection and the application is updated. The Play store or App store will display any updates available when you look up the myAT&T app.
You can remove the application from your phone and re-add it to clear out any temporary bugs which might be affecting it. You will also want to attempt a login on an alternate device, such as a computer, and attempt to pay from there.
Let me know if you are able to login without any issues!
Brett, AT&T Community Specialist