AT&T Galaxy S3 Android 5.1 update [Unofficial]

The official Android 5.1 update for AT&T Galaxy S3 users is something that will never happen. But those S3 users who wish to get one, can now rely on unofficial updates in custom ROMs to install Android 5.1 update on their set. It’s totally worth the effort.

Currently, the CM12.1 ROM has made way to AT&T Galaxy sets, and even though it’s under heavy development, it’s worth a install easily. We expect more ROMs to arrive sooner or later, thus you’ll have variety of Android 5.1 update based custom ROMs to choose from.

What about official update release?

As we said earlier, there will be no official update for AT&T Galaxy S3 from Samsung. Hence, the unofficial updates remain the only way, and perhaps better too, to run the 5.1 update of Google’s Android OS on your S3 at AT&T.

Benefits and drawbacks of the unofficial update

On the plus side, you get to use the latest Android OS, with all new features and animation tweaks Google deemed will lift your experience. And then there are huge customization options in CM12.1 that takes your style and use of Android phone to next level. There’s lot looking forward to CM12.1 really.

On the negative side, you have to do some extra effort of installing a custom recovery first, to be able to install a custom ROM. It’s not hard and is good to learn stuff, something that will come to your aid on every Android phone buy you make in your lifetime. Warranty gets void when you root or install recovery on your Android device, but since your Galaxy S3 is already quite old, the risk isn’t huge.

Given what you’re getting — Android 5.1 update! — the plus totally dominate the minus side.

Removing the unofficial update?

Simple flash the latest AT&T Galaxy S3 firmware back and your device will be back to as AT&T and Samsung wanted it to be. That will remove custom recovery also together with custom ROM, but we don’t think you’ll ever go back to official firmware.

Note: You know, because this ROM is not an official Samsung Android 5.1 update for AT&T Galaxy S3, there are chances you could find few kinks at some of its corners. Any major bugs will be reported below.

AT&T Galaxy S3 Android 5.1 Lollipop update

Sr. #



Major Bugs


CyanogenMod 12.1


Development page | By: amf66

  1. ROM
  2. Gapps

If camera gives trouble, try open camera from play store.
Also, use VivaVideo for video recording if it’s a problem.

NOTE: When downloading a ROM, do check its development page first for newer and more stables builds with less bugs, if available. Since the ROMs are under development, especially the Android 5.1 ones which are getting better week-by-week, there is more reason to check for newer version of the ROM.

More Android 5.1 based ROMs to be added as and when available.

Supported devices
  • AT&T Galaxy S3 by Samsung, model no. SGH-i747
  • Don’t try on any other Galaxy S3 set with different model no., or any other device whatsoever

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 and Gapps file to your device’s internal storage and remember the location where you save them.
  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. Make a backup. 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. Wait for the backup to finish, it’s a time consuming process.
  5. Wipe your device. Once the backup is finished, do this: tap on Wipe, then Advanced wipe, and then select Cache, Dalvik/ART cache and Data. Then do the “Swipe to wipe” at bottom to ready the device for ROM flashing by erasing the cache, dalvik cache and data in one shot.
  6. Install ROM now. Go back to the main menu of TWRP recovery and select Install. 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.
  7. Also install the Gapps the same way as ROM.
  8. Go to back to recovery’s Main menu, select Reboot » select System.

Your device will now reboot with Android 5.1 update!

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

Android 5.1 update is also available on:
Posted by
Kapil Malani

A die-hard Liverpool FC fan, Kapil is a big fan of Batman, Android and street Cricket. In that order, probably. Email: [email protected]