This is for NOUGAT 7.1.1. (and possibly beyond) There is a special procedeur to make flashtool work with the latest firmwares for Nougat ..
This tutorial has been updated 6-26-17 and has the latest V26 kernel, latest SuperSU, TWRP, steps to take.
You will need to download the special Flashtool file here
Download and paste and overwrite it in this location C:\Users\enter the current pc users log in name here\.flashTool\devices\F81XX. This is very critical to make Flashtool work with the newest Nougat updates. Without this file it will not update. Proceed with the update as usual and allow the Flashtool to update the phone. Then proceed with the rooting process.
So as most of you know by now, the F8132 Xperia X Performance has to be bootloader unlocked to get it rooted. That link is my tutorial to get the bootloader unlocked. You also need a special Kernel to allow things on the phone to keep working. I wont explain why. Just trust me, you have to install a new kernel.
Ive gone through the whole process of unlocking and rooting my F8132 and made instructions as I went along. Why did I make these instructions when you can do a search and see someone else also made instructions? Well, because their instructions suck and I had to look all over the internet to fill in the holes where their instructions had huge important parts missing. Its a rather complex procedure especially for most people who have no clue what they are doing.. So basically I wanted my own personal instruction manual for quick reference and alos felt compelled to share my instructions so here with you.
These are my instructions, Some others will do it a different way but this way is what I did and my phone is working 100% and rooted.
Before you Root and install TWRP you need to go back to my link and unlock bootloader..
1) turn your phone off. After its turned off, hold the volume up button while plugging the phone into your pc to get into fastboot mode. Your computer should already have installed drivers when you did the bootunlock procedure.
2)download Boot img, TWRP img, Kernel, SuperSu
Save the 2 img files to the Android Platform folder in your PC here C:\Users\enter the current pc users log in name here\AppData\Local\Android\sdk\platform-tools . Save the Kernel zip and SUperSU zip file to an SD card and put the card inside your phone to access it through TWRP later in the process. Keep in mind that the Kernel may be updated by its developer. So you should check out that persons thread here and check for any updates of his kernel here. Do a "date last modified" list of the files on that page by clicking on the grid view box on the upper right portion of the screen just under the "sign in" button. This helps you see what files have been updated in most recent order.
3) you will open a cmd prompt in this folder by holding down your right mouse button and clock on the shift key then release the mouse button. This will open a pop up window where you can choose to " open command window here" when the cmd window opens, copy and paste this "fastboot devices" press enter button, your computer should respond with this ......CB512A697c fastboot.......This lets you know that your phone is in the correct mode and ready to be programmed.
4)now you will install the boot img by copy and pasting this in cmd line "fastboot flash boot boot.img" The PC should tell you OKAY with some other irrelevant info.
5)now you will install the twrp img by copy and pasting this in cmd line "fastboot flash recovery twrp-3.0.3-0-dora.img" The PC should tell you OKAY with some other irrelevant info.
6) Now you will install Kernel, and SuperSU. Turn off phone. Wait 5 seconds. Then hold power button a volume down button. As phone boots unleash power button while still holding volume down button, wait for the Sony logo to appear then release the volume button to initiate TWRP. Swipe to allow modifications then choose "Install" to install the zip files. Navigate to the SD card that has the kernel and SU zip files. Click on them to install. Reboot. TWRP migth ask if you want to install the TWRP app before the phone starts to reboot. Just say no. After that, a few seconds later, the device reboots and then the Phone might go throw optimization process which takes some time. You will notice the counting of optimized files. Be patient.
7) Reboot, then in your device, turn on USB debugging and turn on OEM Unlocking by going to Settings, then about phone. Go all the way down to build version and tap on it about 7 times. This will unlock Developer Options menu. To go into Developer Options once it is unlocked goto Settings, then Developer options . This menu is where you must turn on usb debugging and OEM Unlocking to proceed with the procedure. Your phone is rooted and can be backed up and restores with TWRP.
When doing a backup with Twrp, backup System and Data
When doing a full restore, wipe only System, Data and the cache files. Do not ever delete your SDcard with the backups on it.
If you get stuck in a boot loop you will have to restore your phone with the Updated version of flashtool.