UCLF5 — Update AT&T Skyrocket to Latest ICS Android 4.0 Build


It’s been almost 8 months since Ice Cream Sandwich (ICS) Android 4.0 came out, but AT&T Galaxy S2 Skyrocket owners are still waiting for it. A few Android 4.0 firmware have been leaked for it in past months, but the official update still hasn’t yet been released. And now, another Android 4.0 firmware has been leaked – UCLF5, which you can flash on your Skyrocket to try out ICS while you wait for the official release.

Important NOTE: This is not a final or official update, so it can have a few bugs and issues and some things may not work correctly. It also contains new bootloaders, which can brick your device if something goes wrong, so make sure to read the instructions carefully.

Read on to find out how you can update your AT&T Galaxy S2 Skyrocket to UCLF5 Android 4.0 firmware.


This firmware and the guide below are compatible only and only with the AT&T Samsung Galaxy S2 Skyrocket, model number i727. It’s not compatible with any other device and may render an incompatible device unusable. Check your device model in Settings » About phone.


The methods and procedures discussed here are considered risky and you should not attempt anything if you don’t know completely what it is. If any damage occurs to your device, we won’t be held liable.

How to Install UCLF5 Ice Cream Sandwich Firmware on AT&T Galaxy S2

  1. This procedure will wipe all your apps, data and settings (but it will NOT touch your SD cards, so don’t worry about those). Backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you.
    Important! Don’t forget to at least make a backup of your APN settings, which you can restore later if your data connection does not work after installing the ROM. Use the backup guide to find out how.
  2. Download and install drivers for the phone on your computer.
    Download Drivers  |  Alternate Link 
  3. Download the firmware by following the download link on the original download page. On the download page, click on the link next to the File URL text as shown below in screenshot to get the direct download link.
  4. Double-click on the downloaded I727UCLF5_OneClickBin_DEABC2C0A29DD59C387453B159AF9730.exe file to run Odin, which will be used to flash the firmware on your phone.
  5. Now, boot into download mode on the phone. To do this, turn off your phone. Plug in your USB cable to the computer, but not to the phone. Then, holding the Volume Up and Volume Down buttons on the phone, plug in the USB cable to the phone while holding those buttons. Once the Download mode screen shows up, let go of the buttons.
  6. The Odin screen will say “Added!!” in the message box below when the phone is connected to the computer. If it does not, make sure you have the proper drivers installed on the computer.
  7. Click on Start to start the flashing of UCLF5 on your Galaxy S2 Skyrocket.
  8. Wait for the procedure to finish. After flashing is complete, the phone will reboot, and you’ll get a PASS message (with green background) in Odin. You can now safely disconnect your phone. What to do if Odin gets stuck: If ODIN gets stuck and doesn’t seem to be doing anything, or you get a FAIL message (with red background) in ODIN, disconnect the phone from the PC, close ODIN, remove battery, re-insert it, then repeat the procedure from step 4.
  9. If you run into any roadblocks while flashing the firmware, let us know and we’ll try to help you out.

The latest Ice Cream Sandwich Android 4.0 firmware is now installed on your AT&T Galaxy S2 Skyrocket. Let us know what you think of it, in the comments below.

10 Comment

  1. Pete says: Reply

    installed yesterday and so for UCLF5 has been stable, some additional tweaks noticed. Battery life is definitely better, make sure you backup your apps, data and APN settings to be safe. All of my restore and were loaded, but to (again) to be safe do a complete backup…Pete, Frisco TX

  2. rgarcia9000 says: Reply

    so far it’s running very smooth, better battery life, no crashes…

  3. That link is no longer there. Do you have another way to download direct without using bitorent?

  4. cpo says: Reply

    Tried to update several times…and keeps hanging at recovery.img. I pull battery and start over, but no success. Now that I have a half-bricked phone…any ideas? :-

    1. cpo says: Reply

      btw…it always hangs at the same point.

    2. cpo says: Reply

      Problem solved. Solution: Changed computers. Funny…it worked just fine on another computer, so if anyone is having issues with hanging, try another system…or different USB ports on your computer, etc.

  5. Agent007 says: Reply

    i keep recieving this error ” MD5 hash value is invalid “.

  6. Jason says: Reply

    After upgrading to UCLF5 internal and external memory is inaccessible. I’ve tried reflashing, downgrading and currently I’m back on 2.3.6 (via kies) both internal and external memory is stilll unavailable.

  7. Rockman says: Reply

    I upgraded two days ago and it went pretty smoothly. Just make sure everything is backed up. The upgrade resets your phone completely. So far it seems to be working well. The only issue I’ve had is now “dzhang” has access to my yahoo contacts and a spam email was sent out. Every time I delete “dzhang” they come back within a few hours. I did some research and it seems to be a Samsung issue with the social hub app, but I didn’t have the issue before the upgrade so I’m not sure what’s causing the problem.

  8. Jotie says: Reply

    Samsung also
    released new user manuals for phones upgraded with ICS (Galaxy II and Galaxy II
    Skyrocket). The new user manuals have significantly more pages (to cover the
    new ICS features) than the previous versions.
    Printed user manuals are available on ebay for those who are interested.

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