You don’t really need to wait for Sony to shoot an official Android 5.1 OTA update towards your Xperia Z Ultra in order to get the update, because you can get it right away unofficially all by yourself thanks to Cyanogenmod custom ROM, CM12.1.

The CM12.1 is already available for the Xperia Z Ultra, and treats the device with pure Android 5.1 pulled from AOSP sources, void of Sony customization and features. The stock Lollipop UI is a treat to use, and even though Sony customizes only a little, we find the stock UI anytime more pleasing.

If you are looking install the Android 5.1 update now, and don’t wanna wait for official update from Sony, go ahead and try out the CM12.1 ROM now. While you’ll get stock Android 5.1 for sure, the features added over it by the CM team are pretty nifty too, quite irreplaceable once you get used to with them.

Installation of Android 5.1 update on Xperia Z Ultra is easy, you only need a custom recovery like TWRP for it. If you haven’t got it already, see the link below in the guide to download and install it. The rest of the process is only easier.

Note: Well, because it’s not an official update from Sony, you could find some small bugs/issues with it.

Bugs
  • Doesn’t blink LED when screen is on
Downloads

Download the ROM file in .zip format from the source development page here, where you could also keep a tab on current issues with the ROM and fixes, if any, available. Also download the Gapps from here.

Supported devices
  • Sony Xperia Z Ultra
  • Don’t try on any other device.
Instructions

Warning: Warranty may be void of your device if you follow the procedures given on this page. You only are responsible for your device. We won’t be liable if any damage occurs to your device and/or its components.

Important Note: Backup important files stored on your device before proceeding with the steps below, so that in case something goes wrong you’ll have backup of all your important files.

  1. Transfer the ROM file package file to your device’s internal storage and remember the location where you save it.
  2. You need TWRP recovery for this. Get it from here. There’s good instructions set there, too. For more help, Google is your friend.
  3. Boot into Recovery mode.
  4. Once in TWRP recovery, take a backup of your current ROM. Select Backup, then do a “Swipe to Back Up” on the bottom of the screen.
  5. Once the backup is finished, select Wipe, then do a “Swipe to Factory Reset” on the bottom of the screen.
  6. Go back to the main menu of TWRP recovery and select Install.
  7. Navigate to the file where you saved your ROM’s zip file, select it and “Swipe to Confirm Flash” on the bottom of the screen. Now wait until the flashing process finishes.
  8. Go to back to recovery’s Main menu, select Reboot » select System.

Your device will now reboot with Android 5.1 update, thanks to CM12.1 custom ROM.

In case you need any help over this, let us know. And, you can thank the developer Saatvik Shukla for this.

Android 5.1 update also available on: