Download and Install Android 4.2.1 XXUFMB3 (Test Version) For Galaxy S3

Finally international Samsung Galaxy S3 also received the latest Android firmware- Android 4.2.1. This firmware version is XXUFMB3 and is only test version firmware. Test version of firmware mean that this OS still consists of some bugs. For your info, Android 4.2.1 bring lot of new features for Galaxy S3, includes: new lock screen and widgets, new notifications panel, new voice command for control more phones function and more.

If you are not developers, then I think that you don’t try flash and run the firmware on your Galaxy S3 because some bugs such as messaging still not stable, the phones OS performance may crash when  running some application and more. But if you are developers and interest to try this firmware on your Galaxy S3, then below is the step by step tutorial on how to flash Android 4.2.1 XXUFMB3 firmware into Galaxy S3 GTi9300 via Odin:

Note: Flash or modified Galaxy S3 firmware will void the phone warranty. Method below is only for your reference and only for the international Galaxy S3 GTi9300.  Try it on your own risk. Before proceed to the step tutorial below, You can refer to the Hints and Tips for more info.
Step 1. You need Samsung Diver to enable your PC able detect and connect to your Galaxy S3. So you can Download Samsung Galaxy Driver (Link) or Downloadand install Samsung Kies on your PC. Restart your PC after installation complete.
Step 2. Download (Link)  the Galaxy Note3 XXUFMB3 firmware(.zip ) and then Extract the file  and now you will get (.tar) file.
Step 3.Go Setting >Developers option to enable USB Debugging on your Galaxy S3  and then Power off your  Galaxy S3.
Step 4.Press your Galaxy volume Down+ Power Button + Home Button to enter Downloading Mode.
Step 5.  Open Odin (download Link) on PC, then connect your Galaxy Note 2 N7100 to PC via USB connect USB.
Step 6.  Make sure Odin Detect your Galaxy S3 (How to know).
Step 7.  Press Odin PDA, then select the  downloaded firmware (.tar) filr.
Step 8.Now click Odin Start button  to Flash the firmware into your Galaxy S3 . Don’t unplug Galaxy S3 connection from computer during the process flashing Android 4.1.2 firmware.
Step 9.That all! Your Phone will reboot once the firmware complete flash into your Galaxy S3. That’s all Enjoys!