Update Xperia U ST25i to Android 5.0.2 Lollipop with OmniROM Custom ROM

While most of the Xperia legacy devices are receiving Android 5.0 update via CyanogenMod 12 custom ROM, Xperia U receives update via OmniROM custom ROM. This custom ROM is based on Android 5.0.2 Lollipop. It is the latest version of Android available at the time of writing. This custom ROM is based on the pure AOSP model which is the true material design introduced in Lollipop. The software is pretty smooth to use and battery-friendly. Like every other new custom ROM, it is not completely free of bugs but it is being fixed in daily basis. The developer of this ROM is active and working hard to make this one a stable ROM. So if you are looking for an Android 5.0 Lollipop based custom ROM for Xperia U, then this is the most suitable choice. Follow this guide for all the installation instructions on installing this custom ROM on Xperia U.


  • Unlock Bootloader of Xperia U. If you do not know how to do it or you have no idea about what it is, then follow this guide to unlock Bootloader of your phone. How to Unlock Bootloader of Xperia Smartphones
  • Install USB Drivers for Xperia U using the drivers installer from the Flashtool installation folder. Download Flashtool from here. After installing USB Drivers, connect phone to PC using the USB cable so that USB drivers are installed properly and connection is established properly.
  • Install ADB and Fastboot Drivers. | Mac ADB And Fastboot Drivers. To avoid the lengthy installation, use the Minimal ADB and Fastboot tools for your PC to make the installation quick. ADB Drivers work best on Windows 7. ADB and Fastboot Drivers might not work on Windows 8 or Windows 8.1.
  • Charge your phone up to 50%. It is very important because phone should not turn off during flashing process. If the phone turns off during the flashing process, it can damage the device.
  • Make a backup of all Contacts and Messages on phone. – Guide
  • Backup SMS Messages
  • Backup Call Logs
  • Make a Nandroid Backup if any custom Recovery is installed already. If not, you will find a custom recovery later in this guide. – Guide
  • Copy all the media files and anything else stored in the internal memory to a PC before flashing to save this data.


The methods involved in flashing custom recoveries, ROMs and rooting your phone are highly custom and may result in bricking your device, and has nothing to do with Google or the device manufacturer that is SONY in our case. Also rooting your device will void its warranty and you will be no longer eligible for any kind of free device services by the manufacturers/warranty providers. In case of any mishap we may not be held responsible. Follow these instructions to the letter to avoid any mishap or bricking. Make sure that whatever you do, you are doing it at your own responsibility.

Required Downloads

Steps to Install OmniROM on Xperia U ST25i

  1. Make sure that bootloader is unlocked and phone is charged to 50% at least.
  2. Extract boot.img from ROM zip.
  3. Copy ROM zip and Gapps zip to phone’s internal memory.
  4. Now turn off phone wait for 5 seconds.
  5. Hold volume up button and connect phone to PC.
  6. The LED should remain blue, which means that phone is in fastboot mode.
  7. Now copy boot.img to Fastboot folder or Minimal ADB and Fastboot installation folder.
  8. Open that folder, hold shift button on keyboard and right-click on mouse.
  9. Click on Open Command Window Here.
  10. Type fastboot devices and press Enter.
  11. It should only one fastboot connected device in return. If it showing more that one, then disconnect any other connected device or close any Android Emulator. Also make sure that PC Companion is completely disabled if installed.
  12. Now type fastboot flash boot boot.img and press Enter.
  13. Type fastboot reboot and press Enter.
  14. While phone is booting up, press Volume up/down/power to enter recovery mode.
  15. In the recovery mode, select Install and navigate to the folder where ROM zip is placed.
  16. Install the ROM zip.
  17. Install Gapps zip the same way and reboot the phone.
  18. Performing factory reset and wiping Dalvik cache after installing ROM is highly recommended!
  19. The phone will boot up to home screen in 5 minutes.
  20. To install Google Applications, copy downloaded Gapps zip file to phone and flash it the same way as ROM. Factory reset is not required this time.
  21. That’s all!

Got any question? Ask me in the comments below 🙂

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Usama M

+Usama M: Ex Farmviller | Android Fanatic | Software Engineer,Founder - TechBeasts.com
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