Update Galaxy S4 LTE to Android 5.1 Lollipop with CyanogenMod 12.1 ROM

Here is how to Update Galaxy S4 LTE to Android 5.1 Lollipop CM12.1 Custom 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.

Android 5.1 Lollipop CM12.1 Custom ROM


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.


AndroidBlog will not 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.


  • 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 > Developer Options.
  • 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 a 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 CM12.1 Custom ROM on Galaxy S4 LTE:

Follow the given instructions to install Unofficial Android 5.1 Lollipop CM12.1 Custom ROM on Galaxy S4 manually:

1:- First of all download the Android 5.1 Lollipop CM12.1 Custom ROM, Google Apps and TWRP recovery to a folder on the desktop of your PC.

2:- Transfer the downloaded ROM, Gapps and TWRP files to the root folder of your SD Card.

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.

4:- While your Galaxy S4 GT-I9505 is in recovery mode. Navigate to the recovery menu and select Backup.

5:- Swipe on the Swipe to Back Up option on the bottom of the screen on your phone.

6:- Perform Wipe of Data, Dalvik cache, Cache and System after the process is completed.

7:- Go back to the main menu of Recovery and select Install zip from SDcard > Choose Zip from sd 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.

8:- Once done, perform Wipe Dalvik Cache again.

9:- Go to the recovery menu and select RebootSystem to reboot the phone.

10:- Now, install the Google Apps package on your Galaxy S4 by repeating the above steps.

10:- 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.


Aamir Jamal

An Android Geek and audiophile who love to read and write reviews/tutorials about gadgets and new tech stuff. He has written 1007 guides and other posts.

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  1. Hi, i tried to flash my galaxy i9505 but when i try to install CGM rom it fails and then i can’t restart my phone becouse it hold in principal booting page (with the samsung galaxy s4 message)

  2. Step 9 should be Reboot > Recovery…. thanks for this though, as formatting System (to force into F2FS) was the step I wasn’t completing so I was getting errors. Sorted now!

  3. Anyone knows how replace dialer. I have one dialer apk official, but i don´t know the files i have replace.
    Thanks for your help.

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