HTC One A9 is a decent smartphone released with Android Marshmallow onboard. Last year, the company updated the device to Android 7.0 Nougat and there is no chance to get the latest Android 8.1 Oreo update on it officially. However, you can get Android 8.1 Oreo on HTC One A9 via official LineageOS 15.1 custom ROM.
The Lineage OS team has released the first nightly build of LineageOS 15.1 for HTC One A9 (code-named hiae), which will bring Android 8.1 Oreo, a host of new features and customizations to the device. If you are interested, here is how to download and install official LineageOS 15.1 nightly build on HTC One A9.
Keep in mind that the LineageOS 15.1 is a nightly build, which means the ROM is not completely stable. Though most things are working well, still there are a few problems remaining.
To install the ROM require unlocked bootloader, TWRP recovery on the device and experience in custom ROM, custom recovery and root. Before proceeding with the below steps, Do NOT forget to back up data on the phone.
Install LineageOS 15.1 on HTC One A9
1. Download latest LineageOS 15.1 (hiae) from here to your phone
2. If you want Google apps and services, download Gapps zip file (Oreo 8.1 compatible) from here to your phone.
3. Boot HTC One A9 to TWRP recovery
4. Select Backup to create a Nandroid backup
5. Select Wipe > Advanced Wipe > Clear data, Clear cache, Clear system
6. Select Install, locate the ROM zip file and swipe right to begin installing the ROM. Once done, flash the GApps zip file.
7. Now, select Wipe and wipe cache and dalvik cache to fix any bootloop issue.
8. Once installation has finished, return to the main menu and select Reboot, then System. Your HTC One A9 will boot into LineageOS 15.1.
Warning: Follow the instruction given above at your own risk. We will not be liable if any damage occurs to your device and/or its components. It is recommended for technically talented users only.
