How to

Update Samsung Galaxy S2 GT I9100 to Official Jelly Bean 4.1.2 UHMS9 firmware

Samsung Galaxy S2

For Samsung Galaxy S2 GT, I9100 model, a new Firmware has been released in OTA, the new Android Jelly Bean 4.1.2 OTA update.  If you didn’t receive this latest Android 4.1 stock update in the OTA, and you want to improve your S2 device with the same, you should follow our manual method to update the device.

To install the official Android 4.1.2 Jelly Bean firmware (UHMS9) on the Galaxy S2 GT I9100 device, you should use the instructions very minutely. But before doing so you should keep in mind that this doesn’t offer big changes in the features but comes to resolve the previously reported bugs only.

This UHMS9 latest update is a more stable version of the JB 4.1.2 OS for your Samsung Galaxy device and you’ll be able to enjoy updates for a few applications and programs that you are using constantly.

This update can be installed only for the unlocked Samsung S2 I9100 devices. You can install the Android Jelly Bean 4.1.2 by OTA or by using KIES app for your device or you can flash it manually. So, this present article will show you a tutorial guiding you how to install this update manually on your S2 device.

This manual installation for the latest official Android 4.1.2 OS can be applied for the S2 owners that have a rooted smartphone. The OTA procedure isn’t supported by the smartphones that have an unlocked and rooted OS. To conclude, if you are running in your device a custom ROM firmware, this guide is necessary, if you want to update your device.

If your device’ warranty was voided, when you’ve installed the custom ROM, you’ll be able to restore it, but you’ll lose the root rights and the unlocking bootloader will be revoked.

Pre-requisites and Guidelines:

  • This tutorial and all the instructions listed here are compatible and can be applied only with the Samsung Galaxy S2 model number GT I9100. So, don’t apply the same on any other device otherwise be ready for the consequences.
  • You need your smartphone, original USB cable and a windows PC to complete this guide.
  • Deactivate or uninstall all the security applications and the settings, which can interrupt the flashing process or can interfere with Odin. Turn off the antivirus and the firewall apps protections on both devices, your S2 and on PC.
  • Back-up all your Samsung Galaxy S2 data store in the internal device’ memory, before proceeding the flashing new ROM OS data like SMS, contacts, call logs, applications, EFS, any images files and videos files, documents and so on.
  • If you’ve installed a custom Recovery image, make a Nandroid back-up for your actual running ROM.
  • Download the Samsung KIES on your PC, and install the compatible drivers for your Samsung Galaxy S2 device;
  • From your S2 menu go to Settings -> Applications -> Development -> USB debugging and enable the USB debugging option.
  • Verify your device’ battery and be sure you have more than 70 % power left in it. Otherwise your device may be forced to shut down during the installation process. This may damage your device as well.
  • Be sure you read all the instructions and all the steps and you’ll apply in the correct order.
  • This article and all instructions listed here are only for educational or instructional purpose, and we can’t be blamed or held responsible for any data loss or damage to your device. Do it at your own risk.

How to Update Galaxy S2 GT I9100 to Official Jelly Bean 4.1.2 UHMS9 OS

  1. Firstly, download the JB 4.1.2 UHMS9 ROM update file from here and save it in your Computer.
  2.  Secondly, download the Odin application and save it in your PC
  3. Now, extract the downloaded update file on your PC and install the Odin software.
  4. Open the Odin app.
  5. Turn off the S2 smartphone.
  6.  Reboot the Samsung Galaxy S2 device into download mode. To do this, you’ll need to press on Volume Down, Center and Power buttons simultaneously.
  7.  Now, when your device is in Download mode, connect the smartphone to the PC using the original USB cord.
  8.  On Odin software verify if the ID: COM section is yellow or blue and the “added” message is visible. Note: In case these settings are not like above, you need to close the Odin application, disconnect the smartphone from the PC by removing the USB cord and after that re-install the S2 proper drivers on the PC. After you have done this, repeat the steps.
  9.  From the ODIN’s app interface select “PDA” option and search and pick the.tar file.
  10.  If there are more files on the extracted downloaded folder package click on: “CSC” and load the CSC file; on “PHONE” field search and pick the Modem file; on the “PIT” field, search and pick the .pit file.
  11.  Now after you pick all the updating package files, click on “Start” from the ODIN and wait to install the latest Android 4.1.2 UHMS9 OS on your Samsung Galaxy S2 device.
  12. When the flashing process completes on the Odin app one “pass” message will be showed.
  13.  Now, disconnect the S2 device from the PC
  14. Reboot your smartphone.

Note: If during the flashing process, you couldn’t apply the procedure, and the Odin get stuck, you have to: close the Odin software and after that to disconnect your device by removing the USB cord, restart your Samsung Galaxy S2 device with a forced restart, and after this you should to re-install the proper drivers. Now, repeat the procedure from the start to finish.


After you have finished the procedure and your device at the first boot gets a boot loop, you have to: stop your smartphone with a power off, after that reboot it into the recovery mode and from there select “wipe data factory reset” & “wipe cache partition” after you wipe the data select “+++go back+++” and at the end, select “reboot system now”.


That’s all! These are all steps that you need to follow in order to successfully complete updating your Samsung Galaxy S2 GT I9100 with the latest official Android 4.1.2 Jelly Bean UHMS9 OS firmware.

After you enter in the new Android 4.1.2 version on your S2, let us know about its performances, and share with us your impressions in our comment section. We are eager to know your feedbacks. Happy Reading!



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