Many Android manufacturers have moved to over-the-air (OTA) software updates after years of relying on the customer connecting his or her device up to a computer (typically Windows). By means of the over-the-air update process, manufacturers can keep customer devices up to date with the latest software releases and security patches, however depending on your carrier and location, there are times when you might not want to wait for the official software release for your particular device. Furthermore, there is an entire cottage industry built up providing Android smartphones and tablets with customized ROMs: for the user willing to experiment, there are many, many options to take. Some manufacturers are more open to the possibilities than others, and Sony are one of the more progressive as they contribute to the Android Open Source Project (AOSP). Sony devices also support over-the-air software updates, but what if your carrier is dragging their feet in releasing a particular software version for your Sony Xperia smartphone? Developers have this covered too: developer Androxyde has built a utility called Flashtool designed to update the Sony Xperia line of devices.
Androxyde's Flashtool is designed to replace the Sony Bridge or PC Companion tool for both Windows and Mac computers. It's able to install new firmware, decrypt firmware from Sony or relock the bootloader on your smartphone. Its origins are that it was designed to provide a graphical user interface to a command line tool, so making the core activity easier for the everyday user to follow. Over the months it has been updated with new features and functions, such as the ability to root devices and the above mentioned bootloader locking and unlocking. Furthermore, as Sony change their devices and how they work, so the Flashtool has had to be updated. For 2015, Sony modified how their Xperia devices connected and updated, requiring Flashtool to be updated with a Flashtool Script required. The last update would communicate with Sony's 2015 devices but would not work with the 2014 and older smartphones, so the developer recommended these customers stick with the old Flashtool version. Now, Androxyde has updated the application to build number 0.9.19.1, which has integrated both the new and the old version of flashing Sony Xperia devices.
Unfortunately, the developer erroneously moved a couple of folders into the wrong location and this can disable the application. If you download the Flashtool but find it does not open, navigate to the C:\Flashtool\x10flasher_lib\winjre folder. In here, you'll find the two offending folders,winjre32 and winjre64. Simply move these folders one level higher to C:\Flashtool\x10flasher_lib and retry the application: it should now work.