Great news to all LG G3 D855 users, you can now root your phone easily on official Android 6.0 Marshmallow 30B firmware without any error.
Backup important files stored on your device before proceeding with the steps, so that in case something goes wrong you will have backup of all your important files.
This site or the developers are not responsible if you damage or brick your device.Do it at your own risk and follow the instructions properly.
First, make sure that you have the Marshmallow update on LG G3 installed and running
What you need for this is a custom recovery such as TWRP recovery, or Cyanogen recovery. Download the TWRP recovery for LG G3 model no. D855 from here.
Root LG G3 D855 official Android 6.0 firmware Marshmallow 30B
Download SuperSU Root package.
1- Once you have installed TWRP recovery, download the file SuperSU from above, and install it using TWRP recovery.
2 For that, move the SuperSU file to your device, and then reboot into recovery mode to access TWRP recovery.
3- Once in TWRP, tap the Install button, then select to confirm the zip file and then do the swipe action at the bottom to confirm.
4 When finished, tap the “Reboot System” button to restart the device.
That is it. Your LG G3 will be rooted.