Ported Official Android 4.1.2 Jelly Bean Firmware for Xperia U ST25i [6.2.A.1.100]

Xperia U users from all over the world was hoping to get Android 4.1 Jelly Bean for their devices but unfortunately Sony refused to provide any further updates, as they’ve already rolled out one major update (Android 4.0.4 ICS) for this phone. Anyways, if Sony doesn’t support this device anymore, developers from XDA community will surely do. These people always search for something new in Android development and eventually come out with astonishing results. Recently, XDA Senior member kontini has ported Xperia Go’s official Android 4.1.2 (Timescape UI) to Sony Xperia U and it works flawlessly. I’ll definitely suggest every Xperia U user to try this out. But remember, this ported version of Android 4.1.2 requires you to have unlocked bootloader and stock or stock based Custom ROM installed in your phone. I am sure you guys already have them but still, it has to be noted.

Now, we’ll look at the features of this ported Jelly Bean ROM. As stated by OP, this ROM is ported from Xperia Go’s latest JB firmware 6.2.A.1.100. It’s pre-rooted so you’ll not require to make strenuous efforts finding the method to root your device after flashing this ROM. Some of the apps & frameworks have been adapted from Xperia P and Themes, Wallpapers, Boot animation & Battery charging icon from Xperia L. This makes it a hybrid ROM i.e. combination of Xperia Go, P, L and of course Xperia U itself. Some more features of this ROM are listed below:

-Advanced Power Menu.
-4×5 App Drawer.
-BRAVIA X-Reality.
-Face Lock.
-Call recording.
-Speed dial settings.

So, don’t hold back to get your hands on. Go for it and you’ll be delighted to see an official Jelly Bean firmware running on your Xperia U ST25i. Steps required to upgrade Xperia U are mentioned below.


Here at AndroidLegend.com, we have written this article at our level best. By any chance, if you brick your device after following this guide, the whole responsibility will be yours. Before attempting this procedure, go through each and every section of this article as most of the problems occur because of not reading them thoroughly. You’ve been warned. Be careful!

There is one more thing you should note – unlocking bootloader / flashing custom recovery, kernel or ROM will void your phone’s warranty (which can be retained by flashing an official firmware though). So, think before you proceed. You’re good to go now.

Xperia U Official Android 4.1.2 Jelly Bean Firmware


This port of Android 4.1.2 firmware is compiled and strictly intended for Sony Xperia U ST25i. Flashing it on any other Xperia / Android device will stop its working and may lead to boot loop. In certain cases, it can also hard brick your phone and may damage the internal hardware.

If you aren’t sure of your device’s model number, you can check the same here: Settings –> About Device (last option in the Settings menu)


  • Battery level below 50% is not recommended. You should charge it up to the certain level (say around 75%) so that device won’t turn off while flashing the ROM.
  1. You may be interested in – Improving Battery Life of your Android Device.
  • This procedure involves internal storage data wiping. Therefore, we highly recommend you to make a backup of your important data such as Contacts, SMS / MMS, Apps, APNs, Call Logs etc. We’ve mentioned few guides below that will help you in backing up your personal data stored on the phone memory.
  • For Backing up Contacts & Messages, follow this guide:
  1. How to Backup Android Contacts and Text Messages (SMS / MMS).
  • For Backing up Call logs & APNs use this guide:
  1. How to Backup Call logs and APNs from your Android Device.
  • Device specific drivers must be installed in your PC. This is required to establish the connection between phone & PC while flashing the kernel. You can download drivers from the link given below:
  1. Drivers for Xperia U
  • (Most Important!) In order to flash the Custom ROM, device bootloader must be unlocked. If you’ve not unlocked it already then follow this guide.
  • Custom Recovery like Clockworkmod is also required to flash a Custom ROM. If you’ve not installed it yet then use RecoverX tool mentioned in this guide for installing the same.

Note: Above two steps shouldn’t be skipped as they are very essential to flash Android 4.1.2 firmware. You can’t proceed further without completing them.

Procedure to upgrade Sony Xperia U ST25i to Official Android 4.1.2 Jelly Bean 6.2.A.1.100 Firmware

For the sake of simplicity, we’ve split the procedure part in 3 sections namely downloads, kernel flashing & ROM flashing.


  • Download ported official Android 4.1.2 Jelly Bean 6.2.A.1.100 Firmware – Link #1
  • Download experimental kernel file  – Link #1

Note: You can also use the kernel file provided in the ROM package. If that is the case then you don’t need to download and flash the experimental kernel. We’ve mentioned both methods of flashing kernel in kernel flashing section. Choose any of the two.

After downloading these 2 files, copy them to your phone’s internal storage using a USB cable. Don’t rename or extract them else they won’t get flashed.

Steps to Flash Kernel:

Method 1:

This method is applicable for the users that have downloaded experimental kernel build from the downloads section.

  • In this method, we’ll be flashing the kernel through CWM recovery therefore switch off the phone and boot into recovery mode. To get into recovery mode, switch on the phone & when phone starts (during boot logo & LED turns blue), repeatedly press Volume up button.
  • After getting into recovery, select ‘install zip from sdcard’ –> ‘choose zip from sdcard’ and locate the kernel file. Select and confirm it by pressing on “Yes – Install Experimental-U-11c.zip“. This will flash the kernel.
  • For flashing the ROM, refer ROM flashing section below.

Method 2:

This method is applicable for the users that haven’t downloaded experimental kernel build from the downloads section.

  • Download Fastboot files (on PC):
  1. Fastboot Files for Sony Xperia U.
  • Extract ‘ADB_Fastboot.zip’ to any convenient location on a computer. You will find five files inside your extracted folder.
  • Switch off the phone and boot into fastboot mode. To do so, Connect your phone to PC. While connecting, press & hold Volume up button to trigger fastboot mode (this won’t work unless you’ve installed drivers in PC).
  • On PC, open the ROM package (Unofficial_Stock_JB_XU_6.2.A.1.100_V9.zip file) and extract boot.img from its root directory to any convenient location. Now, move boot.img inside the extracted folder.
  • Open extracted folder and open runme file.
  • Now, type the following command to flash the kernel (while keeping it in fastboot mode). Note, if you get any sort of error while flashing the kernel then it’s most likely because of not installing drivers properly.
fastboot flash boot boot.img
  • After flashing the kernel, disconnect phone from computer. Now, boot it in recovery mode. To do so, switch off the phone, switch it on again, when it restarts (during boot logo & LED turns blue), repeatedly press Volume up button. Your phone will land in recovery mode. Note that, your phone won’t boot in recovery mode unless you’ve installed a custom recovery like CWM (refer the link given in Pre-requisites for the same).
  • For flashing the ROM, refer the ROM flashing section below.

Steps to Flash ROM:

  •  After flashing kernel, boot into recovery mode.
  • Make a nandroid backup of your current ROM so that it can be restored back in case if anything goes wrong. Nandroid is nothing but a complete backup of your installed ROM. To backup your current ROM, select Backup and Restore option from the main menu & on next screen, select backup. Now It will make a nandroid backup of your whole system. Wait for the backup process to get finished.
  • Select wipe data/factory reset & subsequently wipe cache partition to wipe the data & caches respectively from the phone memory.
  • After wiping data, select Mount and Storage option from the main menu followed by these options: format /data’, ‘format /cache”.
  • Finally it’s time to flash the ROM.
  • Select ‘install zip from sdcard’ & then on next screen select ‘choose zip from sdcard’. It will show the list files & folders located on internal storage of your device. Navigate to the ROM file that you’ve copied earlier, select it using power button (unless you’re using touch recovery) & confirm the installation by pressing on ‘Yes – Install Unofficial_Stock_JB_XU_6.2.A.1.100_V9.zip’. This would start the installation process.
  • Wait for the ROM to get installed (this will take around 2-3 Minutes). After ROM gets installed successfully, your phone will land in the recovery mode again.
  • Now, select ‘reboot system now‘ to restart the phone. First start-up will take more time than usual, so be patient.
  • After getting into the homescreen, restart the phone again. Second restart also might take few minutes to boot the phone.


Voila! You’ve made it. Unofficial port of Xperia Go’s Official Android 4.1.2 Jelly Bean firmware is up and running on your Xperia U. Do lets us know your experience with this firmware. If you need any help then don’t hesitate to drop a comment below, we’ll be glad by helping you out. Enjoy!

Comments (14)
  1. bhumik October 7, 2014
  2. Stef September 8, 2014
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  4. Makaveli July 30, 2014
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  6. nilesh prajapati April 27, 2014
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    • Navin July 9, 2014
  9. Yuri V. April 16, 2014
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