INSTALLATION INSTRUCTIONS
http://www.xperiablog.net/2016/03/12/install-xperia-marshmallow-using-flashtool-and-xperifirm-guide/
- Download the FTF firmware file
- Ensure all drivers are correctly installed on your computer as highlighted in Part 1 of the guide linked to above
- Follow Part 3 of the guide to flash the firmware to your Sony Xperia device
XPERIA FIRMWARE DETAILS
This is official stock Sony Xperia firmware.
Model: Sony Xperia X Dual (F5122)
Firmware version: 34.3.A.0.194_R2D
Region: France (Generic) [1302-3382]
Android version: 7.1.1
Xperia X Dual (F5122) 34.3.A.0.194 France Generic 7.1.1
Sony Xperia X Dual (F5122) Android 7.1.1 firmware - Generic France