Hi @JPOW52690!
Accessing your MyATT account is so important, especially while on the go. I would love to work towards a resolution to get this fixed for you!
Since you have had this issue logging in on the application, have you been able to log in on the computer? I recommend using the same login information to access your account via the webpage.
Clearing cache partition can often help with this issue. You’ll want to power the phone off, press and hold the Volume Up, Home and Power buttons at the same time. Once the phone vibrates release the Power button only. You’ll continue to hold onto the volume up and home button until you see Android System Recovery screen. You can use the Volume keys to navigate and select WipeCachePartition. Pressing the power button will act as enter and begin the process, once you see done, you’ll want to power the phone off and back on.
After completing this step you will want to attempt to log in to the app again and see if you get the same error. If the issue persists, a factory reset of the phone will be the next step. Our Device Support page can get you all the steps you need. Once you reach the page, please select the LG V20 > Tutorials> Troubleshooting> ResetDevice. If there is any information on the phone you don’t want to lose, a backup will need to be completed prior to the factory reset. You can find the steps in Tutorials> Back up & reset.
I hope this information is helpful! Thanks for reaching out!
Michelle, AT&T Community Specialist