After the Android phone is bought back, the manufacturer has appropriate time to provide system updates for the device. There are many Android systems, but whether the firmware upgrade will lead to data loss is the same in principle. Here, Bian Xiao will explain the firmware upgrade of flyme OS. Upgrading the firmware will not cause data loss, but please clear the data when upgrading in the following situations, otherwise it may lead to boot failure: 1, degraded; 2. Major version upgrades, such as upgrading from 3. X to 4. x； ; 3.YunOS firmware and Android firmware brush each other; 4. It has taken root; ; 5. After installing security software, the Android signature vulnerability was patched. When updating the firmware under other circumstances, please do not clear the data. User data upgrade is not clear, and various user data such as contacts, chat records and game progress are not lost after upgrade. However, it is recommended to back up data regularly in case of computer failure or loss of mobile phone. Note: Clearing the data will delete the user data (including contacts, short messages, applications and all mobile phone contents except the data on the storage disk), so be sure to make backup synchronization.