Official guide for upgrading LG G3 to Android 6 Marshmallow

I wanted to upgrade my LG G3 D885 international version to Android 6 Marshmallow, and I found multiple links with multiple tools for doing the upgrade.

OTA (Over The Air) upgrade was not working and always telling me that I'm running the latest version, while I was running Android 5.0 Lollipop.

I contacted LG support via email asking about official way, and they told me just install the LG PC Suite & perform the check & upgrade from the software.

Just download the LG PC Suite, and connect the mobile, and click button "Upgrade Check", and follow the instructions.

After I finished the upgrade, I made a factory reset as I was suffering from battery draining issues, and I have seen several posts regarding this reset that it will most probably help. You can view how to perform the factory reset using this link.