Xperia C5 Ultra suddendly restart

[salgadoc]

Xperia C5 Ultra suddendly restart  after no evident cause. No heating, No app running, no gaming or video playing/recording. It's not on a constant frecuency. It could be one or two days or even a week before it begin restarting several times. I've already tried restoring the phone, update it and nothing works. It's a black version. My brother have exactly the same phone in white, we bought both the same day and he has no problems.Thanks!!

[Luis84]

I have the same issue did you fixed it?

[Mihaiuc]

Hello Sony! I posted the same message in the section regarding marshmallow issues.
I really hope to get an answer.
I m mike, I bought a Sony xperia c5 ultra dual in december 2015. All things went Perfect untill the update to marshmallow.
I use a Sony smartwatch 3.
After the update, the bluetooth and the wi fi don't seem to work, the batery drains much faster than before, and, the most frustrating thing, the phone restarts whenever he wants.
I read the topics and I deleted android wear. For the moment, the phone is ok, but I wonder why did I buy a smart watch?
Anyway, I really hope Sony will fix the problem because me and my family use sony devices. Actually, the reason I bought the c5 is because we were very pleased with the old xperia sl.
But now...I really start to think I made a big mistake. Thank you for your suoport!

[Carlbien]

How to repair this restart always can u do something