The following guide updates the HTC One M8 smartphone to Android 6.0 Marshmallow using a new custom ROM, namely the official CM 13 Nightlies. CM is of course short for CyanogenMod and nightlies means this installment gets nightly updates making each day that slightly more stable than the last. Android updates are notoriously slow on the HTC devices that come with the Sense UI due to the fact that they require extra work in collaboration with Google to get the update working well with Sense. If you do enjoy using HTC flagships and plan on staying loyal to the HTC name, we recommend at least getting to know custom ROMs so you aren’t waiting so long to try out the latest versions of Android like the Android 6.0 Marshmallow available here.

REQUIREMENTS

• The following guide is only for the HTC One M8. You can use it with any One M8 variant from any phone carrier network and any model number. However, it must be the One M8 and not any of the other devices from the HTC range.

BEFORE WE BEGIN

• Download the HTC USB drivers to your computer before starting the guide. That way your device can connect to the computer without any trouble with communicating.
• You should backup your applications using the helium backup tool from the Google Play Store. Do not try storing your app data using Titanium for rooted users. The CyanogenMod ROMs are not supporting Titanium at this time.
• We recommend taking the NANDroid backup during the guide before you wipe data. Wiping the data on your device is mandatory in between flashing custom ROMs which is why you must use the NANDroid feature to take a full backup. You will see this from your custom recovery just as the backup option.

HOW TO UPDATE HTC ONE M8 WITH CM 13 NIGHTLIES BASED ON ANDROID 6.0 MARSHMALLOW

• Download the CM 13 Nightly cm-13.0-20151127-NIGHTLY-m8.zip from here.
• Download the Google Gapps if you want to have the stock Google apps on your device. You’ll need the Gapps for Android 6.0 Marshmallow builds.
• Connect your HTC One M8 to the computer where you downloaded the above file.
• Transfer the ROM over to your internal storage SD card and make sure it’s the root of that SD card.
• Unplug the M8 from the computer.
• Reboot the M8 into the recovery mode.
• First things first: take the NANDroid backup option for a full backup of your device.
• Now navigate to the wipe data/factory reset and wipe your device clean.
• Navigate to the Install option rom the recovery mode menu.
• Browse your SD card for the cm-13.0-20151127-NIGHTLY-m8.zip file.
• Confirm you do want to install that file on your device by swiping the confirmation bar on the bottom of the display.
• Navigate back to the main recovery menu and choose the reboot system option when the ROM is flashed.

Now your HTC One M8 device will reboot in the normal mode and with your new CyanogenMod 13 custom ROM based on Android 6.0 Marshmallow.