After being out for Samsung Galaxy devices, the unofficial CM 10.2 test build is now here to be flashed on the HTC One smartphone. CyanogenMod team is still working on releasing its official CM 10 based on Android 4.3. Till then, let's update our HTC One to Android 4.3 based CM 10.2 unofficial custom firmware.

Prerequisites toupdate HTC One to Android 4.3 JB CM 10.2 custom firmware - unofficial:

Backup any important data from your HTC One as a complete wipe will be required during the flashing process.Enable USB debugging option on your device:Settings>DevelopmentOptions>USB debugging.Your device must be rooted, unlocked and installed with a recovery tool like TWRP or CWM.Your HTC One must be charged to at least 60% of power.

Note:the tutorial is only focused on HTC One - please do not try it on other Android devices.

How to update HTC One to Android 4.3 JB CM10.2 custom ROM:

Required files: downloadthe CM 10.2 unofficial ROM zip for HTC One fromhereand save it on your computer. Do not extract the contents. Also download the Google Apps Package for HTC One from this link.

Connect your HTC One to your computer using a USB cable and copy both the zip files to your smart phone’s internal memory card.Disconnect the USB cord andpower off your HTC One.Boot it into HBOOT mode.Next perform a Nandroid backup of your current OS; important step to revert back to current state. Go toBackup>backup and restoreon CWM.Now wipe data: from CWM recovery mode, selectwipe data / factory resetand confirm the process.To flash the CM 10.2 unofficial custom ROM for HTC One, selectinstall zip from sdcardfollowed bychoose zip from sdcard.Locate the CM 10.2 Android 4.3 zip and confirm the flashing process.The ROM installation process will take several minutes, so be patient.When done, follow the above step for GApps package installation on your HTC One.Return back to main recovery menu and reboot your device into the CM 10.2 unofficial custom OS. First boot takes a good few minutes so kindly be patient.

Awesome! You have successfully flashed the unofficial CM 10.2 custom firmware based on Android 4.3 Jelly Bean on your HTC One!

For more, visit the XDA thread.