Two weeks ago, OnePlus released the OxygenOS Open Beta 3 test firmware for the OnePlus 8 and OnePlus 8 Pro. As it turned out, a serious problem was found in the system.
What is known
Some device owners have lost all data after installing the update and restarting their smartphones. Moreover, many victims even there was no way to avoid this, as their machines rebooted automatically. There were also those who tried to rollback to the old version of OxygenOS 10, and then flash OxygenOS 11 Open Beta 3 again, but that did not help. All information was deleted again.
OnePlus has already acknowledged the problem and has withdrawn the firmware. If you managed to install the update, but your device has not rebooted yet, then the manufacturer recommends installing this application, and then creating a backup and only then restarting the smartphone.
Source: Android Authority