Samsung Galaxy S3 Android 4.2.1 Firmware leaked – I9300XXUFMB3

It’s a busy time at Samsung as they work on the Galaxy S4, which has been confirmed for a March 14 announcement in New York, but that doesn’t mean they’ve forgotten about their current flagship device. The first Android 4.2.1 firmware for the Galaxy S3 has been leaked courtesy of Sammobile, showing Samsung’s dedication towards software support yet again.

Android 4.2.1 isn’t such a major step forward as Android 4.1 was, but it still brings noticeable new features and improvements, including faster and smoother switching between apps. A list of new things in the leaked firmware, which has the build number I9300XXUFMB3, is below.

  • Improved Ripple effect on Lockscreen
  • Widgets on lockscreen
  • Daydream
  • New additions in Notification Center
  • Notifications are more actionable
  • Voice Command (let’s you control various parts of the phone using voice commands)

The firmware is available for download and can be flashed on your Galaxy S3 if you’re interested in trying it out. We have a step-by-step detailing the installation process, which you can use for help if you’re new to this. But first, there are a few things you need to keep in mind.

Flashing the firmware will increase the flash counter on your device and void its warranty. You might also need to wipe all data on your device to make the firmware boot up or to get rid of issues like app crashes. If you’re not willing to take those risks, it’s best to steer clear and wait for the official Android 4.2 update.

Continue reading to find out how the Android 4.2.1 firmware can be installed on the Galaxy S3.


The procedure described below is only for the Samsung Galaxy S3, model number I9300. Do not try it on any other device, not even on the US variants of the Galaxy S3. Check your model number in the Settings » About phone menu.


The methods and procedures discussed here are considered risky, so try them out at your own risk, and make sure to read each step carefully before attempting anything. We will not be held responsible if anything goes wrong.

How to Install I9300XXUFMB3 Android 4.2.1 Firmware on Galaxy S3

  1. [Important] You might need to wipe the data on the phone to make the firmware boot up properly, which will wipe all data including the internal storage. First, backup installed apps and personal data such as contacts, messages, bookmarks, etc, by referring to our Android Backup Guide for help. Then, copy everything from the internal storage to your computer. Your microSD card won’t be wiped.
  2. Download and install the software Kies on your computer, which will install the necessary drivers for the phone.
    Download Kies
    You can also download the drivers directly — download from here: 32 bit (x86) Windows | 64-bit (x64) Windows
  3. Download the firmware.
    Download Firmware
  4. Extract the file downloaded in step 3 on the computer to obtain a file named I9300XXUFMB3_I9300OJKFMB3_HOME.tar.md5 (the file name may end at .tar, which is normal). This is the actual firmware file that we need to flash on the phone.
  5. Download Odin. If you are new to this, Odin is a Samsung program used to flash stuff – firmware, kernels, etc. – on Samsung phones. We’ll use Odin to flash the firmware file obtained in step 4.
    Download Odin3 v3.04 | Filename: Odin3_v3.04.zip
  6. Extract the contents of the Odin3_v3.04.zip file to a folder on your computer.
  7. Now, turn off your phone and wait for it to shut down completely.
  8. Then, put the phone into download mode. To do so, press and hold these keys together: Volume Down + Home + Power till the phone turns on and shows a Warning!! screen. Then press Volume Up to enter download mode.
  9. Open Odin by double-clicking on the Odin3 v3.04.exe file obtained in step 6 after extracting Odin3_v3.04.zip.
  10. Important! Connect your phone to PC now. You should get the message “Added !!” under Odin’s message box in the bottom left.
    • If you don’t get this message, make sure you installed drivers correctly (using Kies or directly) as given in step 2. If it still doesn’t work, try changing to another USB port on the computer and also use the USB ports on the back if you have a desktop PC.
  11. Click on the PDA button in Odin, then browse to and select the I9300XXUFMB3_I9300OJKFMB3_HOME.tar.md5 file obtained in step 4 above.
  12. Important! Do not make any other changes in Odin except selecting the required files as given in step 11. Leave all other options as they are. Make sure Re-Partition check box is not selected.
  13. Now, make sure you took a backup as explained in step 1 before continuing, then click the Start button in Odin to start flashing the firmware on your phone. When the flashing is complete and is successful, you’ll get a PASS message (with green background) in the left-most box at the very top of the Odin, and the phone will automatically reboot. When you see the Samsung logo, you can safely unplug the cable.
    • What do if Odin gets stuck or doesn’t do anything: If ODIN gets stuck on setup connection or at any stage of this process after you’ve hit the Start button, and doesn’t seem to be doing anything, or if upon completion of the process you get a FAIL message (with red background) in ODIN, do this: disconnect the phone from the PC, close ODIN, remove battery for 4-5 seconds, re-insert it, turn phone on in Download mode again, and do the procedure again from Step 9.
  14. [Important] What to do if phone doesn’t boot or you run into issues: After you get the PASS message and the phone reboots, the phone might get stuck at the booting animation. Also, if the firmware boots up, you might see some apps not working correctly. If that happens, perform the following steps to make it boot/work properly. Remember that these steps will wipe your personal data like contacts, apps, messages, etc. If your phone has already booted and the firmware is working fine, stop reading the guide here, your phone has been updated successfully:
    1. Boot to recovery mode — for which, first power off phone (by removing battery and reinserting it), wait for 5-6 seconds, and then press and hold Home + Volume Up + Power keys together till the screen turns on, then let them go to boot into recovery. Once you are in recovery mode, use volume keys to move the selection up and down and home/power key to select the option.
    2. Go to Wipe data/Factory Reset and select it. Select Yes on next screen.
    3. Then, select reboot system now to reboot the phone, which will now boot properly.
  15. If you run into any roadblocks while flashing the firmware, let us know and we’ll help you out.

The Android 4.2.1 firmware is now installed on your Galaxy S3. Don’t forget to play around with it and let us know what works and what doesn’t, in the comments below.

Via: Sammobile