Share your experience!
Have a problem with vibration feedback. When I write a text message the phone vibrates at first, but after a number of characters the vibration dies. The phone stops vibrating when it rings and does not work Sony diagnostic test. To get the vibration alive again I need either to tilt the phone horizontal or shake it. That's not just right..have been trying to do several factory resets but it does not work. It must be a hardware problem?
It would be wise to visit a sony service.Do you use any 3rd party apps for messages?
Force shut down the device:
See if that encounters again.
I have tested force shut down but it still dont working properly. 
Take the phone to a sony service,see what they say.Contact xperia care through the link on my other post.
I have had similar issues with my Z1 compact, a hard shutdown worked once, so did shaking it lightly etc etc but it now pretty much doesnt work at all.
I think it is more a hardware issue and unfortunately as i was just outside the 2 week exchange window (thanks O2, 9 years of giving you money and no help at all in store, City London). So it is being collected by courier, thanks O2 on phone, and returned within 3 days either fixed or replaced.
Not sure who i think is the worst after my O2 instore experiecne, Sony and a error riddled mobile or O2 and their pathetic instore customer service.
Hello!
I have the same problem but my hands sometimes jaf called Service to inquire about the error. I received a reply telling me to turn on the phone the wrong safe mode if it works there for when you do it turns off all apps if it works there, he said that then it might be an app that allows to make them so. But if it does not work then pours you should connect your phone to your computer and do the install but do not forget safe safety copy of everything you have in your phone so you do not get something away.