Sony says that it will be sending out a software update to fix the issue sometime this summer. In the meantime the manufacturer suggests powering off your phone several times a day, especially when charging the device. And Sony also recommends that unsatisfied Xperia Z3+ and Xperia Z4 owners contact the Sony service center.
Those who have experienced the issue while testing an Xperia Z3+ say that the handset gets too hot while playing games, watching Netflix videos in HD, or when filming a video. As we showed you the other day, an Xperia Z4 run through the CPU-Z system identification tool showed the Snapdragon 810 SoC running as hot as 154 degrees fahrenheit.
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source: GSMInfo (translated)