The Flashtool is Sony’s own accessory for manually flashing firmware files on the Xperia smartphone and tablet range. The only catch is you must have an unlocked boot loader or else you cannot use the tool. The same is handy for people into customizing the device and flashing a custom ROM or custom firmware. You must have root access before you can flash either.
The 0.9.18.4 version comes with several notable changes including moving the progress bar back, manual GIT sync and more accurate file decryption. You can view the full change log from here. The earlier version 0.9.18.3 comes with 1.8u25 java and IaguCool gets the mentions on the About US page. The last major update is back at the 0.9.18.1 version where the team added a few tweaks.
According to the official post from XDA Developers, the current version comes with a warning for those using the Sony Xperia Z smartphone. Sony added the “boot bundle” and you want to bundle those from 0.9.13 and flash from the same number only. You can read more about that here. It’s a serious threat that can soft-brick your device, so check out what they are saying before updating.
After downloading the latest installment you can click the “devices” tab and “check updates’ for your device. The following screen pulls the list of devices for you to choose. Select the model number that belongs to you and it will tell you the latest firmware version that’s available. navigate to Settings > About Device to find out your model number.