25 February 2018
The HTC One M8 is an Android smartphone which is now over three years old and the last major official software support it received was an update to Android 6.0 Marshmallow. And now, the latest major Android version is Android 8.1 Oreo which is currently available only on Google Pixel and Nexus devices. But thanks to the openness of the platform and custom ROMs, you have the option to update your old HTC One M8 to Android 8.1 Oreo with ease.
In this tutorial, we will tell you how you can install LingeageOS 15.1 based on Android 8.1 Oreo on your HTC One M8. It is a fairly easy to follow tutorial with no complicated steps or tweaks if you are already familiar with unlocking of the bootloader, rooting, and flashing ROMs. If you are not, we would suggest you learn the basics before proceeding with any of these steps. But if you are still willing to go ahead, you can do so at your own risk.
So with those disclosures out of the way, let's get started. The first thing that you need to make sure is that your HTC One M8 has an unlocked bootloader, custom recovery TWRP installed, and all of the important data has been backed up. The next step is to download the necessary drivers for your HTC device and enable USB debugging from within Developer options under Settings. If you don't have Developer options enabled already, you can do so by tapping build number seven times (available under About Phone under phone settings). And it goes without saying that your device should be charged to at least 80% before starting with the tutorial.
Steps to Install LineageOS 15.1 (Android 8.1 Oreo) on HTC One M8:
Step 2: Connect your Android device to the PC/laptop via USB cable and copy above-downloaded files to phone's internal storage.
Step 3: Disconnect the device from the PC, power it off, and reboot into TWRP custom recovery.
Step 4: Go to the Advanced section and wipe clear dalvik, cache, system, and data files.
Step 5: Once you have done that, go to the main interface of TWRP and tap Install. Select the custom ROM to begin the installation.
Step 6: You will see two options Reboot and Wipe Dalvik Cache after the installation is complete and you need to select the second one.
Step 7: After this, go back to the main interface and install the GApps package like you installed the ROM.
Step 8: Once the installation is done, wipe dalvik cache again and reboot.
It is worth mentioning the first boots after a fresh ROM installation are known to take some time which can run for 10 minutes. So just be patient until the device boots up. Once it boots, your HTC One M8 is already rocking LineageOS 15.1 based on Android 8.1 Oreo.