Guide to Update Galaxy S2 I9100 to UHMS8 Android 4.1.2 Jelly Bean Official Firmware

Feb 27, 2013

Samsung has released UHMS8 Android 4.2.1 Jelly Bean Official Rom for Galaxy S2 I9100. The ROM puts Galaxy S2 users just one notch behind the latest Android firmware out there.

Also, read: Guide to Root UHMS8 Android 4.1.2 Jelly Bean on Galaxy S2 I9100

Disclaimer:This guide will be using ‘Odin’ as a took to flash the official firmware on your Galaxy S2 I9100. During the process, you might lose all your existing installed apps and personal settings. It is therefore necessary for you to follow the guide carefully. Also, please, do mind that this tutorial is only for Galaxy S2 I9100. Don’t try this guide in any other Android device.

Android 4.2.1 UHMS8 Firmware Details:

Version: 4.2.1
Date: 2013-02-12


  1. Android 4.2.1 Jelly Bean I9100UHMS8 for Galaxy S2 I9100
  2. Odin 3.07

Guide to Update Galaxy S2 I9100 to UHMS8 Android 4.2.1 Jelly Bean Official Firmware

  1. Download and Extract to get a file with .tar extension in the unzipped folder.
  2. You will then extract Odin zip file to get Odin3 v3.07.exe.
  3. Switch your phone off. And make sure that you wait 5-6 seconds to confirm complete the power down cycle.
  4. You will then put your Galaxy S2 I9100 phone in Download Mode by pressing and holding down the Volume Down button, alongside Home and the Power button, until the screen flashes the Samsung Logo. After a few seconds of that, the phone will enter download mode.
  5. Run Odin3 v3.07.exe with Administrator rights.
  6. Now that you are all prepared to root your phone, connect your Galaxy S2 I9100 with your PC. You will then see a notification appear in Odin in the bottom left saying “Added!!”. If for some reason, you do not see the said notification, try another USB port. If that too doesn’t work, then reinstall the USB driver. Once you successfully see the “Added!!” notification in Odin, you are good to go. Also, check for COM port being depicted by a number in ‘yellow’ to make sure that you have successfully added your device.
  7. Select the following files in Odin at their respective tabs from extracted UHMS8 firmware folder :
    • Click the ‘PDA’ Button, and select the .tar file extracted in Step 1.
    • Click the ‘Phone’ Button, and select file with *modem* in its name (Ignore, if this file does not file exist).
    • Click the ‘CSC’ Button, and select file with *csc* in its name (Ignore, if this file does not file exist).
    • Click the ‘PIT’ Button, and select the .pit file. Use only if you got it while extracting in step 1 above, otherwise ignore it.
    • In Odin window, make sure Auto Reboot and F. Reset Time checkboxes are selected. Please make sure that Re-Partition checkbox is selected, only if you are using a .pit file.
  8. Hit the ‘START’ button to begin the flashing process.
    Once the flashing process is completed, the phone will automatically reboot and you will see a ‘Green’ PASS notification in the top-left-most box. You can unplug the device from the computer now.

If you have followed every point described in the guide, your Galaxy S2 I9100 should now be running Android 4.2.1 Jelly Bean build I9100UHMS8. If there are any issues, feel free to post in the comments section for our staff to take a look at it.