Share your experience!
What is it you're trying to do?
What does the message say?
Try performing a system repair as this will often fix issues however this will factory reset your phone so backup any files etc first
Switch off your phone and unplug from Pc (Hold volume up and power for around 10 seconds)
Start PC Companion and select Support zone then Update my phone/tablet then in Blue Repair my phone/tablet and follow the onscreen instructions - When prompted connect your phone still switched off holding volume down or back button - This should start the repair or reformat process
If you are using Windows 8/8.1 or a 64bit operating system then adjust the settings for PC Companion and run in compatibility mode and chose Windows 7 or XP
If you are using Android 4.4.2 then the built in VPN will surely not work even if you repair the phone because it is a bug present in the Android itself. Everyone are facing that issue. This problem can be solved only if Sony provides us with KitKat 4.4.4 update.The only available solution is you can go for some third party applications like VPN in touch etc which you can easily install from Google Playstore.