Hello Everyone! I have urgent questions if anyone is available to help. My friend wants to upgrade his iPhone 6s IOS 9.1 (I think it is the original version, but I'm not sure) to IOS 12 or 12.3.1, but he is afraid of losing his data(ex; pictures, videos, voice memos, notes, apps and so on) as well as that the new version might shorten the battery life and the performance of the iPhone will be less than 9, especially he only has 2 to 3 GB available in his iPhone . He wants to update it because most of the apps require 10 IOS and more, and regarding security matters. I told him to back up his phone before upgrading it and he did that through PC iTunes, but he is afraid of that after upgrading the software, the iTunes will refuse to restore the data r that iTunes did not back up everything. What do you think guys? Will upgrading from very old ios to the newest one cause a data lost? if yes, then what should he do? Having only 3GB available on his phone will make a problem? Should he upgrade his IOS through iTunes or the phone itself (from settings)? which one is better? Can iTunes refuse to restore the backup? I just told him to upgrade it, but I'm so afraid that his data will be lost because of me Thank you in Advanced. Your response will be highly appreciated!