[Sony Xperia T2 Ultra] theokon:
A step-by-step-Version (summary)

Here comes a step-by-step-Version (summary) of all the "Posts"s needed for rooting Lollipop 5.1.1 on your Sony Xperia T2 Ultra (Dual).

The copyright is by the "Post"-authors like rituraj_singh and abcdjdj (I took the links to the posts nearby the description of the step) and by w0lfdroid.com, xperiafirmware.com and the software-producers.

I only wanted to create a step-by-step-summary. There is no garantuee which garantuees success using the summery! No responsability dad it does not destroy your mobilephone. Use it at your own risk! Thank you to the original "owners" of the posts. I hope the summary is ok for them! Otherwise contact me.

Time: maybe 1 hour or 2 hours

Tipp: if you until yet did not install Android 5.1.1 on your Xperia T2 Ultra Dual you do not have to follow the steps which are describing how to download the older Firmware via XperiFirm, but you should have installed the FlashTool just for the drivers (You won't use it directly). You can use the steps describing how to root the older Firmware using KingRoot, than continue with step 7.

1) Install the Androxyde FlashTool on your Computer: http://www.flashtool.net/downloads.php or found on the XDA-Forum, install the ADB-Packages (ADB, ADB-Drivers) on your Computer and make the ADB-Command part of the "path"-Variable of your Computers Terminal (see Google)

2) Install XperiFirm (cause easy for beginners): open the FlashTool and click on the "XF-button" near the "plus-in-a-square"-button and the "flash"-button.

3) After having installed the XperiFirm-Tool open it and click on "Xperia T2 Ultra (tianchi)" and select "D5322/XM50H (dual)"

4) Than click on the "Check-All"-Button over the Line "Latest Release"

5) Click on "MENA Latin" in the "Market"-Line and than on the "19.3.A.0.472 / R3C" and download it (having activated "unpack automatically")

6) Go to "xperiafirmware.com/8-firmware/58-sony-xperia-t2-ultra-dual-d5322" and download it (see chapter "1." on the website ), but do not flash it

7) Download the newest PRF-Creator (ZIP) from the following XDA-Forum-Link and unzip it: http://xdaforums.com/crossdevice-dev/sony/tool-prfcreator-easily-create-pre-t2859904

8) Download the newest SuperSU-ZIP from chainfire (https://download.chainfire.eu/696/SuperSU). and paste the ZIP in the unzipped PRF-Creator-folder: https://download.chainfire.eu/696/SuperSU

9) Now copy the .ftf-file (Firmware) downloaded from xperiafirmware.com also in the unzipped PRF-Creator-folder and open the PRF-Creator.exe

10) The PRF-Creator asks for the .TFT-File (select the one you downloaded from xperiafirmware.com) and for the SuperSU-ZIP-File (select the one downloaded from chainfire)

11) Select in the "Include"-field: "Kernel"; "FOTA-Kernel"; "Modem" and "LTALable", also "Sign ZIP" and "Legacy Mode"

12) Click create and wait until finished

13) Copy the created "flashable-prerooted.zip" from your unzipped PRF-Creator-Folder to the external SD-Card of your Device

14) BackUp your mobilephone using the "Sony PC Companion" or simular software like Wondershare's "MobileGo"

14a) Control if you have unlocked your Boatloader (normally it's locked) and if it's locked, go to the "Sony Mobile Developers Unlock Bootloader Website" and follow the instructions there Important: You could have to install ADB and Sony's ADB-Drivers (find ADB using google) and the Sony FlashTool "Emma" will not work with the Xperia T2 Ultra Dual

15) Shut down your phone and start it holding the "Volume-down"-Button while plugging in the USB-Cable (it won't show more than a black screen)

16) Close "XperiFirm", wait until it finished and then click on the "Flash"-Button and select in the new window "Flashmode" and "OK" (obviously)

17) Select the Firmware you downloaded before with XperiFirm (19.3.A.0.472) and select in the "Wipe"-Field: "APPS_LOG" and "USERDATA" (!!!important!!! otherwise problems)

18) Click on the "Flash"-Button and wait until it's done (sometimes the flashtool has problems with the files - dont worry: shutdown the FlashTool and retry it once more)

19) Unplug the mobilephone from the USB-Cable, start it and follow the instructions

20) After having prepared the mobilephone go to "kingroot.net/wap/download" and download KingRoot (sometime trouble with the site, try it once more)

21) Afterwards enable the DeveloperMode (settings - About Phone - click "build number" 7 times) and enable the "unknown sources" (settings - Security - unknown sources)

22) Install KingRoot and root your Xperia T2 Ultra Dual

23) Install "Terminal Emulator" from the Google Play-Appstore to your device and open it

24) Go to "http://www.w0lfdroid.com/2015/05/How-to-Remove-Replace-KingUser-KingRoot-with-SuperSU.html" and download the newest "Replace KingUser with SuperSU.zip" and unpack it to your device's intern memory (!!!important!!! otherwise no function)

25) In the Terminal Emulator App enter "su" for gaining "root"-access ("Enter" obviously), than enter "sh /sdcard/mrw/root.sh" and wait until it finish (it will open SuperSU)

26) Actualize the file as requested by SuperSU and, after having had success, reboot your mobilephone

27) Install a Root-Checker-App from Google Play Store and control, if you see a window from "SuperSU", otherwise repeat the last steps

28) Go to "https://goo.gl/lg6I2t" or visit directly the XDA-Forum-Post of abcdjdj (http://xdaforums.com/showthread.php?t=2764408) and download his "TWRP-KK-T2_DUAL-V3.img" or newer

29) Shut down your mobilephone. Afterwards hold the "Volume-Up"-Button while plugging in the USB-Cable (it shows only a black screen) and connect it to the Computer

30) Check if you have installed all fastboot drivers for your device, then open the "Command Line" of your Computer "as Administrator" and enter: "fastboot flash boot (path-to-the-file-downloaded-in-the-last-step)/TWRP-KK-T2_DUAL-V3.img" and click obviously "Enter"

31) Now unplug your mobilephone, than hold the "Volume-down"-Button and the "Power"-Button at the same time: TWRP-Recovery will start

32) Select "Wipe", than "Advanced Wipe", than select "intern. memory", "dalvik", "cache", "data" and "system"

33) Swipe to Wipe

34) Go to TWRP's home (twice times the "back"-Button) and select "Install", than "external SD-Card" and select "flashable-prerooted.zip" and confirm the warning, than SWIPE to INSTALL (flashing)

35) Wipe the Dalvik-Cache

36) Reboot into System and follow your mobilephone's instructions

37) Install a Root Checker App from Google Play Store and control if it's rooted, afterwards install the backup of your mobilephone made at the beginning

38) Install "Titanium Backup" and disinstall (after having done a backup of the app you want to delete) Apps you do not want

39) Install "Link-to-SD" from GooglePlay, prepare your external SD-Card with a partition manager (using your Computer) and copy all possible apps completly to the SD-Card