Install Official CyanogenMod 12.1 (Android 5.1.1) on Galaxy S2 I9100

Samsung Galaxy S2 owners can now enjoy Android 5.1.1 Lollipop and the new Material design UI on their device with CyanogenMod 12.1 ROM. Cyanogen team has released the first official build (CM12.1 Nightly) for Galaxy S2 that bring Android 5.1.1 along with many new features to the phone. Interested S2 users read on to know how to flash the ROM.

Go through the easy guide given below to install the official CyanogenMod 12.1 (Android 5.1.1) on your Galaxy S2. Before you start installing the ROM, note that this is a nightly build, which means it is unstable, so you may come across some bugs while using the phone. However, if you are craving to get your hands on the Android 5.1.1 Lollipop on your Galaxy S2 go ahead and install CM12.1.


Note: The below procedure will wipe your device, so backup your phone data such as personal files, images, videos, messages, emails, contacts, apps, SMS, Contacts, Call Logs, Bookmarks, etc.

Install Official CyanogenMod 12.1 on Galaxy S2 Intl Variant (i9100)

Pre requisites: Your Galaxy S2 must be rooted and custom recovery like CWM or TWRP installed.

Disclaimer: Follow these instructions carefully. Do it at your own responsibility. We cannot take responsibility for anything that goes wrong.

1. Download the official CyanogenMod 12.1 [HERE] ROM zip file and Gapps [HERE] zip file for CM12.1.

2. Copy both downloaded files to your phone’s SD card.

3. Boot Galaxy S2 into custom recovery mode. To do so, turns off your phone, press, and hold Volume Up + Home + Power Key together.

4. From custom recovery, wipe cache partition, data and dalvik cache.

5. Select “Install Zip from Sd Card” and then select “Choose Zip from Sd Card” (Use Vol up/ Down keys for selection)

6. Select CyanogenMod 12.1 ROM .zip file that you placed on your SD card, then select “Yes”, and let the installation process to complete. Do the same for Gapps zip file.

After completing the installation, your phone will reboot (for the first time, it will take little long time). Enjoy Lollipop!


If your Galaxy S2 stuck in a boot loop (does not start up), power off it and boot it into recovery mode.

From recovery, do wipe factory data, cache and dalvik cache. Once done reboot your S2. It will remove all the system junks as well as solve boot loop and restart issues.

Any doubt, feel free to ask us. We hope our guide is easy to use. Please leave us feedback through comment box below.

Kannan is a computer and Android enthusiast, a blogger by passion and a tech freak. His always ready-to-help attitude, knowledge and hard work is what drives him.


  1. hamed

    Feb 14, 2016 at 1:34 am

    after installing every thing is ok but if you turn off while wifi is on in the second time the wifi won’t be able to find any wireless network.

  2. deepan

    Nov 23, 2015 at 10:05 am

    Samsung s2 cell i will update 5.1.1 android but sim cards will not accepet in this android why ??

  3. anand

    Nov 22, 2015 at 2:59 am

    after installing cm12.1in my galaxy s2 i9100
    when I turn of my screen the phone reboot
    how to solve it
    please answer

    • Kannan

      Nov 23, 2015 at 8:19 pm

      After a complete wipe (cache, system, dalvik), repeat the procedure again.

Leave a Reply

Your email address will not be published. Required fields are marked *