Following the Nexus 4 and Nexus 10, the Galaxy Nexus is also receiving the Android 4.2.1 update from Google, at least for the US “takju” variant purchased from the Play Store. And, as always, while Google takes its time to roll out the update to everyone over the air, it is already available for downloading and flashing manually for those interested.

Android 4.2.1 is a minor bug fix update (only ~1MB in size) that mainly focuses on fixing the issue of December missing in the calendar in the People app, along with Bluetooth instability issues. It doesn’t unfortunately fix the reboots, battery drainage, and performance issues some users have been experiencing, so some might be disappointed by that, though disabling background sync in the Currents app has been known to help with lag.

There’s a guide below that will help you flash the Android 4.2.1 OTA update manually on your Galaxy Nexus. Those have a custom recovery like ClockworkMod or TWRP installed can simply download the file (link is below), copy it to the phone, boot into recovery, and install the update just like any custom ROM. However, make sure your phone isn’t rooted or has any other modifications to the ROM, otherwise the update will fail to install.

NOTE: This update can be installed only the US Play Store, aka “takju” variant of the Galaxy Nexus, and you’ll need to be on a completely stock (unrooted) Android 4.2 ROM with build number JOP40C to be able to update. Check the build number in Settings »  About phone before proceeding.

To check whether you have the takju variant or not, download the Android System Info app from the Play Store, open it, click the “System” button on top, expand “BuildInfos”, then check what it says in front of “Product”. If it’s not takju, do not proceed.

How to Install Android 4.2.1 Update on Galaxy Nexus (takju)

  1. First, make sure you have the drivers installed for the phone on the computer. Get them → here if you don’t have them installed already.
  2. Download the OTA update file.
    Download Link | Filename: 1d62212ba0a9.signed-takju-JOP40D-from-JOP40C.1d62212b.zip
  3. Download Fastboot, which includes the adb files needed for flashing the update.
    Download Fastboot | Filename: Fastboot.zip
  4. Extract the Fastboot.zip file on your computer to get a folder named Fastboot with four files inside it. To keep things easy, extract the Fastboot folder to drive C.
  5. Then, copy the update file downloaded in step 2 to this “Fastboot” folder you just obtained.
  6. Turn off the phone, then boot it into stock recovery. To do so, first boot into the bootloader mode by holding down the Vol Up + Vol Down + Power buttons together till the screen turns on. Then, using the volume buttons, scroll till you see the “Start” text change to “Recovery mode”, then select it using the power button to boot into stock recovery.
  7. You will then see an Android with a red exclamation point. Now hold down the Power button then press the Volume Up key to see the recovery menu.
  8. Select the apply update from adb option in recovery, by scrolling to it using the volume buttons and selecting it with the power button.
  9. Connect the phone to the computer. Wait for the drivers to finish installing.
  10. On the computer, click on Start menu » All Programs » Accessories, right-click on Command Prompt and click on Run as administrator. If you are using Windows 8, this can be done by right-clicking on the extreme bottom left corner of the taskbar, then selecting “Command Prompt (admin)”.
  11. Now, perform the following steps in the command prompt to flash the Android 4.2.1 update:
    1. Navigate to the Fastboot folder which you obtained in step 6. For example, if the Fastboot folder is in drive C on your computer, enter cd C:Fastboot in command prompt (and press Enter) to navigate to the folder.
    2. Then, enter adb devices. If your Galaxy Nexus has been detected properly, you will see a device ID show up in command prompt. If nothing comes up, make sure you have installed the drivers (step 1).
    3. Finally, to flash the update, enter the following command:
      adb sideload 1d62212ba0a9.signed-takju-JOP40D-from-JOP40C.1d62212b.zip
    4. After you enter the above command, you will see the “sending: sideload” message in the command prompt, and once it reaches 100%, the update will start installing on your phone.
  12. After the update finishes installing, select reboot system now on the phone to reboot it and boot up into Android 4.2.1.

Android 4.2.1 is now up and running on your Galaxy Nexus. Do let us know if you notice any improvements or changes in it other than the mentioned above. Enjoy!