These are the instructions to root HTC One A9 on Android 6.0 Marshmallow. Once you allow your device access to the root file system, you can begin installing large number of apps you couldn’t up until now.

REQUIREMENTS

• You must have the HTC One A9 bootloader unlocked before you can get root access on the device.
• You must have installed TWRP recovery on your HTC One A9 before you can get root access with this guide.

BEFORE WE BEGIN

• Download the HTC USB Drivers from our USB driver downloads page. You can also find the universal ADB driver on the same page which you might prefer to install.
• On your smartphone, point to the Settings and see if you can see the Developer options. If you can then proceed to the next step. If you cannot then point to the Menu > Settings > About Device > tap the build number 7 times or until it says you are now a developer. That is letting you know that you will now find the Developer Options available from the Settings.
• Make sure you enable the USB Debugging Mode by pointing to the menu > Settings > Developer Options USB Debugging Mode. Check the box and leave the Developer Options and it will remember your settings.

HOW TO ROOT HTC ONE A9 ON ANDROID 6.0 MARSHMALLOW

1. Follow our detailed guide on how to set up ADB and Fastboot on Windows for Android if you deleted it after installing your custom recovery. You do not need to download it again if you already have it on your computer.
2. Download the su.zip from here.
3. Download the Superuser zip from here.
4. Unzip the SU file you downloaded on the computer and move the contents over to the same folder you created when you followed the TWRP recovery guide.
5. Unzip the Superuser app file to find the Superuser.apk file.
6. Connect the HTC One A9 to the computer if it isn’t already.
7. From within the folder where you have transferred the SU file, hold down the Shift key and right-click the mouse to bring up a new menu.
8. Choose to open a new command prompt window from that menu.
9. Type the command and hit Enter: adb push su.img /data/su.img
10. Navigate back to the main recovery menu and select he reboot System option to reboot your device back into the normal mode.
11. Now you need to install the Superuser app on your device which will act as the app which grants root access when the apps request it.
12. Transfer the Superuser.apk file you unzipped earlier to the devices internal storage SD card.
13. Unplug the device from the computer.
14. Launch a file manager on your device and install that Superuser APK file.
15. Once done, that Superuser will remain on your device and continually allow the rooting permissions when called upon after you download the apps.

That’s all you need to root HTC One A9 smartphones. Once you complete all three guides, you should have unlocked the bootloader, installed a custom recovery and got root access to your internal system. Now you can install any apps that require root access from the Google Play Store and install custom ROMs.