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Install CyanogenMod 12 Android 5.0.2 ROM on Galaxy S2 GT-I9100

Here is how to download and install CyanogenMod 12 Android 5.0.2 for Galaxy S2 GT-I9100. Android 5.0.2 Lollipop update has been rolled out for a few luckiest Android devices yet, and Galaxy S2 I9100 is one of them as it also received support for this latest Lollipop update via CyanogenMod 12 ROM, thanks to the CyanogenMod team. This ROM has not been officially released, but users have tested this unofficial build of CM12 ROM on their Galaxy S2 devices and found it more stable than other builds released previously. We don’t say that there are any bugs in this ROM. This is an unofficial ROM so some minor bugs with HD video recording and storage might be expected.

Your Galaxy S2 GT-I900 should be rooted to taste this pure build of Android 5.0.2 Lollipop. If you have not rooted your device, then you can get root access to its internal system using Chainfire’s CF Auto Root and then you’ll need to install KitKat compatible custom recovery on the Galaxy S2 GT-I9100 to flash CM12 ROM on it. So if you want to flash CyanogenMod 12 Android 5.0.2 for Galaxy S2 I9100 then follow the given step by step guide carefully.

CyanogenMod 12 Android 5.0.2 for Galaxy S2 GT-I9100


This guide is only working with the international variant of Galaxy S2 GT-I9100 only. Do not try it any other variant. Check the model number of your device by going to Settings > About Phone


AndroidBlog will not responsible for any damage occurred to your Galaxy S2 I9100 before or after the installation of CyanogenMod 12 Android 5.0.2 for Galaxy S2. Proceed at your risk.


  • Is highly recommended to take backup all your data and settings via a custom recoveries tool such as ClockworkMod (CWM) or TWRP Recovery to create a full image of the phone.
  • Make sure that you have correctly installed the correct USB drivers for the Galaxy S2 on your PC. You can download Galaxy S2 USB Drivers from this link.
  • Enable USB Debugging Mode on the Galaxy S2 by going to Settings > Developer Options.
  • Verify that the battery level of your phone is not less than 70% to prevent shutdowns while flashing the ROM.
  • The Galaxy S2 should be rooted having a CWM recovery installed on it.
  • The bootloader of the device must be unlocked.

Required Files:

Steps to Install CyanogenMod 12 Android 5.0.2 ROM on Galaxy S2 GT-I9100:

Step No 1: – First of all, download Unofficial CyanogenMod 12 Android 5.0 custom ROM ( on your PC for the Galaxy S2.

Step No 2: – Plug your device with the PC using its USB data cable and make sure to mount USB mass storage of the phone.

Step No 3: – Transfer downloaded CyanogenMod CM12 ROM .zip file to the root folder of your SD Card on the S2.

Step No 4: – Turn Off the device to boot it into Recovery Mode and unplug it from the PC.

Step No 5: – Next, Turn on the Galaxy S2 by pressing and holding Volume Up + Home + Power buttons at the same time.

Step No 6: – While your Galaxy S2 is now in the CWM Recovery, perform Wipe Data/Factory Reset, Wipe Cache Partition and wait for the process to be finished.

Step No 7: – Also perform Wipe Dalvik Cache by going to “Advanced” and select Wipe Dalvik Cache”.

Dalvik Cache is necessary to prevent boot loop issues etc.

Step No 8: – Go back to the main Recovery Menu and select Install Zip from SD card”.

9: – From there, select Choose Zip from SD card” and find the CM12 ROM .zip file that you have already copied to SD card of your Galaxy S2. Select it by Power button and on the next screen, confirm the ROM installation to initiate.

Step No 10: – Similarly, install Google Apps (Gapps) package on the phone by repeating the above steps.

Step No 11: – After the installation of ROM and Gapps on your Galaxy S2, navigate to “+++++Go Back+++++” and restart it by choosing Reboot System Now from the Recovery menu.

Your phone will be rebooted now, and it will take some time about 4 to 5 minutes to boots up for the first time after flashing ROM and Gapps.

That’s All! You’ve successfully updated Galaxy S2 I9100 to the latest Android 5.0.2 Lollipop via CM12 custom ROM. Don’t hesitate to tell us in the comments area below if you have any question or have a problem regarding the above tutorial to update your Galaxy S2.


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  1. I followed the steps but get a:
    Warning: No file_contextsmount: failed to mount/dev/block/mmcblk0p9 at /system: Device or resource busy
    I can’t do anything anymore on the S2, please HELP

    1. Hi,
      I notice this if an Email is configured with “Push” and Wifi or Internet is not available, like if you are somewhere in the park without Wifi connection and Mobile data is off.

  2. I have a problem (when the screen go off the phone will reboot ) sleep was set to 30 sec, after screen goes off 3 sec than reboot and it keep on doing that. i don’t use the one you have. I don’t remember the links.

  3. this ROM didn’t worked for me.i had to restore the backup as installation aborted as it failed to mount. Please help ?

  4. Just like Hans I faced the same problem today.
    If there is any solution I would love to read & start over. as for now my mobile became a dummy. ****

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