Galaxy S2 I9100
AOKP Nightly ROM brings the latest Jelly Bean update - Android 4.2.1 - to Galaxy S2 I9100

Samsung is likely to release the latest official Jelly Bean update for Galaxy S2 I9100 in the next few days. Those who cannot wait for the official release can now taste the latest Android 4.2.1 Jelly Bean firmware via AOKP nightly custom ROM. The ROM is now available for manual download and installation with this guide.

Key Points to Note

  • AOKP Nightly ROM and the instructions provided in this guide are applicable to the international variant Galaxy S2 I9100 model only. It will not work on any other device. Verify your device's model number by navigating to Settings > About Phone.
  • Users are advised to back up important data and settings to avoid data loss during the Android 4.2.1 Jelly Bean firmware installation process. It is recommended that you back up data manually using this guide, and avoid using ROM manager or Samsung KIES for data-backup as it may brick or damage your device.
  • As the ROM is a nightly build, it may harbour a few untested bugs (such as FC errors, boot loops and boot failures) or broken features. In case you face such issues, you need to reinstall stock firmware or any other stable custom ROM. Be advised that AOKP nightly ROM is a custom ROM based on AOSP release of Android 4.2 Jelly Bean and not an official firmware.
  • Do not forget to do a Dalvik Cache wipe before continuing from Recovery mode
  • Samsung KIES will not recognise your phone after installing AOKP nightly ROM based Android 4.2.1 Jelly Bean firmware
  • The instructions provided in this guide are meant for reference purpose only and do not cover any warranty claims involving device damage or issues arising out of installing the firmware on your Galaxy S2. Users are advised to proceed at their own risk.


  • Verify that the correct USB drivers are installed for your phone on the computer (download Galaxy S2 I9100 USB drivers).
  • Enable USB Debugging mode on your phone by navigating to Settings > Developer Options (if device is running Android 4.0 or later) or go to Settings > Applications > Development (if running Android 2.3 or earlier). Else browse to Settings > About Phone > scroll down to the bottom and select Build Number > tap the Build Number about seven times (if running Android 4.2 Jelly Bean on device).
  • Make sure that your phone has at least 85 percent battery power to prevent unexpected device shutdown (due to battery drain) while installing the AOKP nightly ROM.
  • Ensure that your phone is rooted with ClockworkMod Recovery (CWM) installed on it.


Download Android 4.2.1 AOKP Nightly ROM

Download Google Apps for Galaxy S2 I9100

How to Install Android 4.2.1 Jelly Bean Update on Galaxy S2 I9100 with AOKP Nightly ROM

Step 1 - Connect and mount your Galaxy S2 USB mass storage on your computer with original USB cable.

Step 2 - Copy the downloaded Android 4.2.1 ROM and Google Apps zip files to the root folder on your phone's SD card.

Step 3 - Switch off your phone and unplug its USB cable from the computer.

Step 4 - Press and hold Volume Up, Menu and Power buttons together, until the phone boots into Recovery mode.

Step 5 - In CWM Recovery, perform a full data wipe first. Then navigate to Flash zip from SD card option and hit Power button to select it.

Step 6 - Tap the Power button again and click Choose zip from sdcard.

Step 7 - Use volume keys to navigate to the Android 4.2.1 ROM ZIP file that you copied earlier to your phone's SD card. Then select it by pressing the Power button. Confirm ROM installation on next screen and the installation process will begin.

NOTE: Repeat the step 7 again for installing Google Apps.

Step 8 - After Google Apps is installed, hit Go Back and tap Reboot System Now in the Recovery menu. The phone will reboot and the first boot may take about 5 minutes to complete. So, leave it alone until the process completes.

Android 4.2.1 AOKP Nightly Jelly Bean ROM is now installed on your Galaxy S2 phone. Go to Settings > About phone to verify the firmware version installed.

[Source: Team Android]