Galaxy S2 I9100 Official Firmware UHMS8 Android 4.1.2 Jelly Bean Installation Guide


Now that UHMS8 Android 4.1.2 Jelly Bean for Galaxy S2 is officially out, owners of these devices may now download and install the firmware via Samsung KIES in supported countries.

You may also go for a manual update if in case you don’t see the firmware in SKIES. In line with this, we, at sebertech provide a simple tutorial to walk you through the entire manual installation process.


This tutorial is only intended for owners of Samsung Galaxy S2 I9100 who wanted to upgrade their phones manually.

Also note that this guide is only optional, and therefore, we at sebertech, will not be held responsible for any potential issues that may arise during or after the installation process. However, it is very unlikely for a device to get busted if you just follow the given instructions precisely as mentioned in this page.

Bear in mind that after flashing official firmware, custom ROM will automatically be replaced by the official stock ROM, which means that all custom ROM installed in it like Paranoid Android, CM10 or AOKP will be lost.

Besides custom ROM, custom Recovery like TWRP Recovery or ClockworkMod will also be lost after flashing. However, flashing of this firmware will not increase binary counter as it officially came from Samsung.

You only have to extract downloaded archives/files ONCE. If the zip file does not contain any csc, pit of modem files, then that means these files are not needed for the installation to get done. Usually, the must-have file for this firmware flashing is the one with extension .tar.md5.

If in case an ODIN message that says “MD5 hash value is invalid” shows up, then that means you have to re-download the firmware to proceed.

DO NOT try this tutorial on any other Android device as it is only applicable for Samsung Galaxy SII I9100.

What to get after the update?

Originally, the Galaxy S2 I9100 came out with Gingerbread platform but now that the official firmware is out, it can already run on Jelly Bean.

Among the key features you will get from this update would include the following:
  • Complete User Interface revamp – UI is now similar to that of Galaxy S3 and Galaxy Note 2.
  • Buttery Smooth Performance & Great Stability – made possible with Project Butter
  • Enhanced camera features
  • New Widgets from Galaxy S3
  • New Lockscreen with Many Customization Options
  • Samsung S Cloud services
  • TouchWiz Nature UX
  • New Notification bar with More Notification Toggles
  • Google Now
  • 2 Home screen modes
  • New Features such as Direct Call, Pop-up Play and Smart Stay
  • Before you begin, make sure you have at least 80 percent battery power on your smartphone to circumvent possible deterrence that may cause a hard brick on your device.
  • Enable USB Debugging to allow file transfer in smartphone and PC.
  • USB Driver installed for Galaxy S2 in your computer.
  • Back up all necessary files stored in your phone, especially the EFS Folder so you can recover important contents easily when needed.
  • Secure ODIN utility for Windows OS. For Mac OS like Ubuntu, use CrossOver Utility
Installation Proper:

1. Download Android 4.1.2 Jelly Bean I9100 UHMS8 Official Firmware for Galaxy S2 I9100 and ODIN 3.07. (Both are zip files.)

2. Extract the official firmware zip file you’ve downloaded, in order to get more files with .tar and some other file extensions.

3. Extract your downloaded zip file for ODIN so you can get the executable file named ODIN3 v3.07 along with other files in the folder.

4. Turn off your smartphone. Be sure to wait 5 to 6 seconds for your action’s confirmation that the device is completely turned off.

5. Switch your Galaxy S2 I9100 into Download Mode. To do so, you have to press and hold the Volume Down, Power and Home buttons simultaneously until you will be prompted with the Samsung Galaxy logo on the screen. A few seconds more and your phone should be in download mode already.

6. Run the executable file ODIN3 v3.07.exe as an Administrator to be granted with Admin privileges, which is necessary to complete the installation process with no hassles.

7. Connect your Galaxy S2 I9100 to your computer with a USB cable. When both devices are successfully connected, you should see an ODIN message box that says “Added!” If you are not seeing the same output, then you try using another USB port to connect both devices. If it still won’t work as it should, then try reinstalling the driver. ODIN’s “Added!” message simply denotes that you may now proceed to the next step. Besides the Added message, a COM port with numbers in Yellow will also appear on your device.

8. Select all important files from the I9100 UHMS8 folder through the following buttons:
  • PDA  button – Click on this button and choose the file with .tar extension with matching *code*on its name
  • Phone button – Click on this button and choose the file with *modem* on its name (disregard if no such file)
  • CSC button – Click on this button and choose the file with *csc* on its name (disregard if no such file)
  • PIT button – Click this button and choose file with extension .pit (disregard if no such file)
9. Put a check on Auto Reboot and F. Reset Time checkboxes in the ODIN window. Do the same with the Re-Partition checkbox if you are using .pit file.

10. Verify if everything is correct, especially instructions on Step 8 and Step 9. If everything is correct, then hit the Start button to instigate flashing process.

11. Wait until flashing is finished. Once done, wait for your phone to reboot. Soon after reboot, you will be prompted with a PASS message with green background. This is found in the left-most box at the very top of the ODIN software.

12. If you see the PASS message, then you may now unplug the USB cable to disconnect your smartphone from the PC.

And that’s it! You now have your Galaxy S2 I9100 running on Android 4.1.2 Jelly Bean build I9100 UHMS8. To verify firmware is already updated, check your phone Settings and then About Phone details.

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