Unfortunately, a fully working port of Android 7.0 Nougat based custom ROM is not yet available for Galaxy S3. Most of them are initial builds and facing issues with RIL, Wi-Fi tethering and video recording. Here are two unofficial CyanogenMod 14 custom ROMs for Galaxy S3 (i9300/ i9305) with most things working, but both are still a testing version and cannot be used as a daily driver. Interested Galaxy S3 owners may go through the easy installation guide given below to install the unofficial CyanogenMod 14 (Android 7.0 Nougat) on Galaxy S3 i9300 (international variant) and S3 LTE i9305. Note: The below given files are testing version, which means it contain several bugs. In addition, as they are initial builds, you may not get all the features of Nougat and CyanogenMod.

How to install Unofficial CyanogenMod 14 (Android 7.0) on Galaxy S3

Note: We are assuming that you have already rooted your Galaxy S3 and installed latest version of TWRP recovery on it. Note: Before you start, make sure you have a stock system image to flash back to. Make a system backup from TWRP recovery before proceeding.

  1. Download unofficial CM14 build for Galaxy S3 from here or here (both are different build). Also, download Android 7 compatible Gapps package from here (select ARM and Nano version).
  2. Save both CM14 ROM zip file and Gaps zip file to your S3’s SD card.
  3. Reboot your Galaxy S3 to TWRP recovery. To do so, press and hold Volume Up, Home, and Power button few seconds.
  4. In recovery, perform a full wipe (cache, dalvik cache, data/factory reset) by selecting ‘Wipe’ option.
  5. Now, flash CM14 and Gapps. To do so, select ‘Install’, navigate to ROM zip file and swipe to confirm flash. Repeat the same for Gapps as well.
  6. Before rebooting, once again wipe cache partition and data, and then reboot your phone.

The first boot will takes around 10 – 20 minutes. Once booted up, set up your phone and enjoy Android 7.0 Nougat. Leave your views in the comment section below. (source – 1, 2)