Will updating to Android 7.0 cause my phone to lose all its application data ? If so, how can I prevent this? I own a Nexus 5X, and I wish to update the device firmware from Android 6.0.1 to Android 7.0. When I do this, will it wipe all my phone data (i.e. essentially perform a factory reset) ? I know that my Play Store account has a record of all the applications I use, but I suppose the application data will be lost. I'm specifically concerned about Asphalt 8, in which I've reached a pretty advanced stage. I've heard that Android apps that have data backup enabled save their data remotely in the cloud, but that this doesn't apply to game apps like Asphalt. So my question is,

1. Will I lose all my application data, and specifically my Asphalt 8 data ??

2. If so, how do I backup my data, and without having to root the phone ? What I'd like ideally is to do the firmware update AND get back my Asphalt 8 data (without having to root the phone).
OTA updates don't wipe the device: all apps and data are preserved across the update.

Even so, it's always a good idea to back up your data frequently. As you point out, not all apps support the in-built Google backup mechanism, so it's wise to have a full backup just in case. See our backup tag wiki and top questions to learn about what options are available (whether you've rooted the phone or not).