My camera turns on itself

[Masper]

My xperia z5 camera turns on camera itself and it is so annoying. Why this is happening? I dont even touch camera button. Even my phone locked, my camera turns on.

[Lord_viridis]

Do you have a case that may be pressing the button?

[Masper]

I have case but it is happening without case or with case

[Lord_viridis]

Does the button work as expected in camera app?

[Lord_viridis]

Try booting in safe mode (hold power button, hold finger on "power off" until reboot into safe mode appears) and see if it still happens.

[Masper]

Yes everything is alrigth except this bug. I realize now while it is happening camera isnt work, i mean i cant take any shots only camera vision on the screen. I think this bug came with last marshmallow update.

[Masper]

I will try this if it happens onemore time.

[Lord_viridis]

"I realize now while it is happening camera isnt work, i mean i cant take any shots only camera vision on the screen."
It sounds like the button is opening the app and still remaining in an active state, preventing further use until released.
Try blowing the button area, there may be some debris in the button, try clearing cache and data from settings, apps camera. Or if it doesn't bother you, you can disable the quick launch in camera settings on manual mode.
Last self help is repair installation via Xperia companion pc app, back up first.
Failing all the above, you should contact your local support to arrange a repair.