Guide on how to install Android P 9.0 Developer preview rom on any device.If you are running Android 8.1 Oreo on your Google Pixel, Google Pixel XL, Google Pixel 2, or Google Pixel 2 XL and you are rooted with Magisk, then you may be wondering how you can update to Android 9.0 (Android P). Is it possible to accept the OTA update as a rooted user? Yes, but that depends on several factors. Have you ever modified anything in /system or /vendor? Do you have only Magisk installed and not TWRP? Do you have both Magisk installed and TWRP? Depending on your answer to these questions, it changes what you have to do quite a bit.
Fortunately, you don’t have to worry about the differences in any of the above scenarios if you update using a factory image. I personally always update my device using the latest factory image, and it’s the fool-proof method that accounts for all variations. You can even update without having to wipe your data so long as you are running stock Android 8.1 Oreo. If you are running a custom ROM, however, then you will have to wipe data—so just keep that in mind and back up the entire contents of /data including /data/media onto your PC before you proceed. Finally, you will also need to be sure that your machine has the ADB/Fastboot binaries installed.