Sony announced that it was ending support for the Sony Update Service (SUS) application back in July. SUS has been favoured by many as a no-frills way of updating their Sony Xperia handsets over Sony’s PC Companion software. Whilst Sony removed the download links for SUS, if you already had the software installed it still worked without any problems. Until now.
If you launch SUS now you will be met with the screen below. Sony is directing you to use PC Companion instead. A shame really, but even more reason to perhaps rely on FlashTool/XperiFirm instead going forward.