How to Update Galaxy S4 GT-I9505 LTE to Android 5.1 Lollipop with CyanogenMod 12.1 ROM

The latest Android 5.1 Lollipop update is now available to download for the Samsung’s 2013 flagship smartphone Galaxy S4 LTE (GT-I9505). Thanks to the XDA Developers (AntaresOne & Alucard24) for releasing the Android 5.1 Lollipop update via CyanogenMod 12.1 (CM12.1) custom ROM. So if you wish to experience this 5.1 Lollipop based CyanogenMod 12.1 custom firmware update on your S4 then follow the given step by step guide carefully.

Keep in mind that this ROM is not officially released by Samsung, but this is just an experimental CyanogenMod 12.1 based Android 5.1 Lollipop custom ROM which is developed by the third party developers. Thus, you might face some not functioning features which are yet to be fixed.


This guide containing the CyanogenMod CM12.1 (Unofficial) firmware is only working with the Galaxy S4 GT-I9505 LTE (jflte, including jflteatt, jfltevzw & jfltexx) models. Do not try to install this firmware on any other device or incorrect variant, as a result the device might get bricked. You can check the model number of your phone by navigating to Settings > About phone > Model Number.

Warning: will not be responsible for any kind of damage occurred to your Galaxy S4 I9505 during or after the installation process of unofficial CM12.1 Android 5.1 Lollipop custom ROM. Proceed at your own risk.

Before Getting Started:

  • Create a proper backup of all your existing data and settings on the phone before proceeding to the installation guide using a recommended custom recovery.
  • Enable USB Debugging Mode on the Galaxy S4 by navigating to Settings > About Phone.
  • Verify that you’ve properly installed the Galaxy S4 USB Drivers on the PC.
  • The Galaxy S4 should be rooted with the latest version of custom recovery like CWM or TWRP installed.
  • The bootloader of your S4 must be unlocked.
  • Make sure that the battery level of the Galaxy S4 is at least above 80% before going ahead.

Required Files:

Steps to Install Android 5.1 Lollipop on Galaxy S4 LTE via CyanogenMod 12.1 ROM:

Follow the given instructions to install Unofficial CyanogenMod 12.1 custom ROM featuring Android 5.1 on Galaxy S4 manually:

Step No 1:- First of all download the Android 5.1 Lollipop CyangoenMod 12.1  ROM, Google Apps and TWRP recovery to a folder on the desktop of your PC.

Step No 2:- Transfer the downloaded ROM, Gapps and TWRP files to the root folder of your SD Card.

Step No 3:- Next, turn OFF your Galaxy S4 to boot into Recovery Mode. Turn the device ON while pressing and holding Power + Home + Volume Up keys at the same time till the TWRP logo appears.

Step No 4:- While your Galaxy S4 GT-I9505 is in recovery mode. Navigate to the recovery menu and select Backup.

Step No 5:- Swipe on the Swipe to Back Up option on the bottom of the screen on your phone.

Step No 6:- Perform Wipe of Data, Dalvik cache, Cache and System after the process is completed.

Step No 7:- Go back to the main menu of Recovery and select Install zip from SDcard > Choose Zip fromSD card, then navigate to the root folder of your SD Card where you have saved the ROM, select the ROM and click on Swipe to Confirm Flash option. This process may take some time, so wait for the process to be finished successfully.

Step No 8:- Once done, perform Wipe Dalvik Cache again.

Step No 9:- Go to the recovery menu and select RebootSystem to reboot the phone.

Step No 10:- Now, install the Google Apps package on your Galaxy S4 by repeating the above steps.

Step No 11:- Navigate to the TWRP main recovery menu once the Gapps package is installed and select Reboot > System.

Done! You’ve successfully updated Galaxy S4 GT-I9505 to Android 5.1 via CyanogenMod 12.1 ROM manually.

Let us know in the comments area below if you have any question or trouble while updating your S4 to this CM12.1 custom firmware.


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