I upgraded my Sony Xperia T to Android 4.3 some months ago but it is the last week when I'm suffering of this critical issue.
My phone turns itself off 10 or 20 or 30 times a day. It just happens when the charger is not connected. Said that, it constantly turns off even with the battery at 90% or 100%.
I've already reported it to Sony (via web ticket) and followed their steps (PC Companion and mobile reset, data lost and so on). PC Companion sets the latest firmware (this is, Android 4.3) not the old one coming with the mobile when I bought it two years ago.
PC Compannion procedure did not fix it at all. Even worse, just after the "repair" I switched on the mobile and it took 30 seconds to get turned off again! And then the very same: 10/20/30 shutdowns a day.
To make things clear: The shutdown problem ALSO occurs when I switch on the mobile *without* both the SIM and the SD card, so it is NOT a problem with the SIM or the SD card at all.
There are too many reports like this one in this forum and others. I don't fully understand why this problems happens now and not months ago when I upgraded to Android 4.3, but IMHO it is 100% clear that this is a firmware/software problem.
My mobile is 100% unusable right now. I hope Sony provides a solution ASAP.
