Another possibility is software corruption. If the
AOL mailbox is not available due to software corruption, the application's files might not be in the system. This could be caused by a virus or other software. Performing a hard reboot will force the application to close and reopen. To perform a hard restart, swipe up the screen and double-click the Home button. Once the device relaunches, close any open applications.
See also -
https://globalblogging.com/aol-mailbox-unavailable/
