To avoid unexpected reboot, battery drainage, hang and so on, it’s recommended to set phone to be a new phone while the first sync right after jailbreaking or updating. But there’s inconvenient consequence afterward, that you might loose valuable files like contacts, notes, call history, SMS achieve and so on. Thus, to handle this problem it’s recommended to manually backup your iPhone files before updating iPhone to new firmware. In order to apply this you need to have SSH installed already on your jailbreaked iPhone. So visit this page “Guide to access iPhone file system using SSH for Mac and Windows“.
If you want to back up your iPhone data, you can follow the following link:
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