Developer support for LG G4 is remarkable. It’s just been a day or two that the device has received the official Marshmallow update, and developers have ported the firmware file for rooted users; making it flashable right through TWRP. Here are some flashable zip files that will take your LG G4 H815 variant to Android 6.0 Marshmallow without the complex process of flashing the KDZ file. The listed files are from software version 20A that comes with the official KDZ firmware and includes the system (stock ROM), boot, modem and bootloader zips.

The main advantage about this method is that your bootloader will still be unlocked and you can gain root access later by installing the SuperSU package over this ROM. Moreover, you can also downgrade to the Lollipop ROM in no time.

Although it is stock-based ROM, you may come across some bugs with the notifications that may not work with all apps. To check for possible missed notifications go to Settings> battery/energy saving> battery consumption> ignore optimization. Also, knock code has been removed but will return in a future update.

Unlocked bootloader is required in order to flash the ROM files via TWRP. When coming from Lollipop, you will need to flash at least the system and boot zip files. Modem and bootloader zips may be optional but are recommended. Moreover, do not wipe system partition until after you have flashed the bootloader. So let’s begin with the tutorial.


Marshmallow update (20A) flash files for LG G4 H815:

  • System  — Link | File: (1.33 GB)
  • Modem — Link | File: (39.31 MB)
  • Repacked Boot – Link | File:
  • Bootloader — Link | File: (35.43 MB)
  • Boot — Link | File: (13.08 MB) [Optional]


  • The listed custom ROM is compatible with LG G4 H815 variant only. Do not try it on any other device or variant.
  • Unlocked bootloader is required in order to flash the system and boot images on your G4. To unlock the bootloader on your device, get to the official page.
  • Make sure you have TWRP recovery installed on your device. Download the recommended TWRP 2.8.7+ build from here. For detailed TWRP installation instructions using fastboot, get to our tutorial through this link.
  • You must have device drivers installed on your PC so as to transfer the ROM and Google apps to your device’s storage. Download here.
  • You must fully charge your device or at least to 60%, as the process may take a while.

Backup your Apps and Data

Before you proceed, make sure you backup all your data. This process will wipe all the data from your device except for the internal storage. Hence, a full backup or nandroid backup is recommended. Also backup all your internal storage files just in case anything goes wrong. Take a nandroid backup from the custom recovery before flashing the ROM.

How to Update LG G4 with Android 6.0 Marshmallow Using TWRP

  1. Download all the zip files from the download section (System, Modem, Boot, Bootloader, Repacked Boot).
  2. Now transfer the 4 zip files into your device’s internal storage. Place the zip file where you can easily locate it.
  3. Now reboot into Custom Recovery (like TWRP). To boot into TWRP, first turn off your device and then press and hold volume down and power keys at the same time. If you see the TWRP logo, that means you have successfully booted into the recovery.
  4. Although this is optional, it’s highly recommended that you perform a nandroid backup. To backup, your ROM, tap on backup option in TWRP and select the following elements: System, Data, Boot, Recovery, EFS and swipe right where appropriate, to back up.
  5. Now go back to the TWRP main menu or home screen and tap on the install option. Navigate to the ROM files. Now select modem and on the next screen tap Add More Zips and select system, repacked boot and bootloader in their respective order.
  6. Swipe the confirmation button to proceed with the installation. The ROM will be installed.
  7. Once installed, reboot to system.

If you see the new boot logo, that means you have successfully installed the ROM on your device. If you come across any boot loop or face system errors, try a factory reset from the recovery or you can always restore your previous ROM from the backup.

Also See:

How to Install Stock Firmware on LG G4 KDZ File

For queries, comment down below. If we have helped you, then like and share us on social platforms. If you need help with other devices, let us know.


  1. Yeah the LG Flash Tool may fail several times. But keep on trying and it will. Try using different functions in the tool. Use CSE, CDMA, DAIG/CS_Emergency. Most importantly, flash a lollipop firmware and disconnect from internet during the process. Marshmallow gives errors.

  2. Did you enable adb from Developer Options in your new ROM? Install device drivers again and setup adb and fastboot. Then perform operations. Refer to my “Root Nexus 5X” post on the home page. If you still can’t get TWRP installed then as a last resort, you will need to flash the KDZ. Refer to the KDZ post and it’s done.

  3. The kernel is available that won’t remove the recovery. As you don’t have TWRP, try flashing TWRP using fastboot.

  4. Flash the modem, system and boot one after the other and then reboot the recovery once. Now flash the bootloader. If bootloop still persist, try a factory reset.

  5. Developer support for the G4 is totally lacking for any model except the 815 and there has been pretty limited development for it. I’ve had my US AT&T model for months and there is not even a bootloader unlock or root for it yet.

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