Update the Samsung Galaxy S4 LTE to Android 6.0.1 Marshmallow using the custom ROM designed by the OctOS team. This custom ROM is based on AOSP Marshmallow and you can learn how to install one using the instructions below.

This is a brand new custom ROM for all the Samsung Galaxy S4 LTE models and you should check the guidelines below before starting the flashing process. Check the following links here and here in order to learn more about this release.

Check the following guidelines below before starting the installation of OctOS Marshmallow ROM.

Preparation Steps:

Use this tutorial only with the International Samsung Galaxy S4 LTE "jfltexx" models.
Do not attempt to update any other devices with the files that you will find in this post.

The T-Mobile device that you are about to update using the OctOS Marshmallow ROM has to be rooted and it should be running the latest TWRP Custom Recovery build.
- the installed custom Recovery has to be updated to its latest version, so that it supports the new Android 6.0.1 custom ROM installations.

In the tutorial you will find two additional preparation steps like the NANDROID Backup and Factory Reset process.
The NANDROID Backup creates a complete backup for the ROM that's already installed on your phone, so that you will be able to repair your device in case something goes wrong during the installation.
The Factory Reset process wipes clean the system partition and it allows OctOS ROM to boot after the installation.
Factory Resetting the smartphone won't delete any files from the internal storage.

If you need to save any data from installed apps then you need to use Helium tool.

Use the tutorial only in case you are an advanced user. We cannot be blamed in case you brick your phone nor in case you lose any important data in the process.

Check the whole post and do not skip any steps.

Make sure that the battery charge level of your device is over 50%, as it will prevent your smartphone from powering off during the installation process.

How to flash OctOS Marshmallow 6.0.1 ROM for International Galaxy S4 LTE:

  1. Download the OctOS-MM Weekly zip from here.
    - check here for newer builds.
  2. Download Gapps or Android 6.0 ROMs from here.
  3. Connect the phone to PC via usb cable and transfer both zip files on to its internal storage.
    - after the files are copied you can disconnect the phone from PC.
    - do not unzip the files.
  4. Power off your S4 and then boot it in TWRP Recovery Mode.
  5. First thing that you need to do is to setup the NANDROID Backup for the ROM that's already running on your phone:
    - select the 'backup' option from the Recovery Mode menu.
    - set a name for the file and confirm process.
  6. Apply the 'factory reset':
    - confirm factory reset process and continue to the next step when you're done with it.
  7. Start the custom Marshmallow ROM flashing process by selecting on the "Install" option in TWRP.
  8. Find the OctOS-M-Weekly zip and load it. Confirm the flashing process and don't press any buttons until all files are installed.
  9. After the OctOS ROM is flashed you can flash the Gapps zip, too.
  10. Reboot the phone in normal mode after all files are installed successfully.

Note that the first boot process of this new custom ROM is going to take a while before it loads all the new files.

If you need more help completing the OctOS Android 6.0.1 Marshmallow ROM, then you should tell us in comments.

If installation fails at your first attempt, then you can try to repeat the whole guide more than once. Make sure not to skip any steps and that your phone meets all requirements listed above the tutorial.

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