Those who got update notification,
Take a backup of all important data like contacts, call logs, SMSs, apps, APN and other settings before proceeding further. You may have to perform a clean install of your OS. While for all practical purposes, using Flashtool is safe but there is a very very remote chance of damaging your phone and don’t blame me should it happen.
1. Install Sony PC Companion and/or SEUS. This will copy the necessary drivers to your PC. Connect your phone with USB Debugging enabled and allow your PC to install the necessary drivers.
2. Connect your phone and update or repair your phone with the latest firmware version (right now 14.1.G.1.534). If you update/upgrade, your data will be preserved. If you repair, all data may be lost. So backup everything. Now, your phone is updated with the latest firmware. Keep it aside. We don’t need your phone anymore to create the ftf file.
3. Go toC:\ProgramData\Sony Ericsson\Update Engine\db\13740270\blob_fs folder and look for the biggest three files. The folder “blob_fs” may be located in a different place depending on whether you used PC Companion or SEUS. Perform a search for that folder if you can’t find it. Once you are inside the folder, sort by size and see the 3 largest files were just created (when you updated/repaired your phone). Copy them to somewhere else like D:\firmware.
4. Install Flashtool and open it.
5. Click Advanced > Decrypt Files.
6. Select all the three files and click the right arrow to send them to the right side and click OK. In a moment, you will see a Flashtool pop up window that shows all the decrypted files. Select all and click the right arrow button.
7. Type in the device name next to Device, firmware version number next to Version, and branding next to Branding and click OK.
8. In the Device Selection window that appears, select xperia Z1 and click OK.
9. In a moment, your ftf file will be there in the default Flashtool folder C:\Flashtool\Firmwares
10. Upload it and post the link so that everyone can use it..