Please read this if you considering unlocking the boot loader or rooting your phone.
Please note that you may void the warranty of your phone and/or any warranty from your operator if you unlock the boot loader. You should only unlock the boot loader of your phone if you are an advanced user with good knowledge of the technology and risks involved.
For more information go here http://unlockbootloader.sonymobile.com/
Please also note
The Sony Xperia support team will not be able provide any support, related to unlocking the boot loader or rooting your phone.
We also recommend you to read the below blogposts.
Sony Xperia support team
2012-12-05 04:57 AM
i just updated my xperia u to 6.1.1.b.1.54. i was rooted then afetr the update im not. i would like to update my phone but it always fail. i tried the binary root from xda but it wont work anymore. help me root my phone.
2012-12-05 09:59 AM
did your phone unlocked bootloader yet? if unlocked you need to flash your kernel to 6.1.1.B.1.10 then root it it work 100% for me even version of Stock ICS 6.1.1.C.1.0