I reset my sony Xperia C4. After that the theft protection appears and asks me to authenticate. When I try to authenticate it says "Sorry Xperia Helper Has Stopped. And I can't authenticate.
Click on 'emergency call'. Type in this number ##7378423#*#. It will fail, but after a while, your google account will ask you to log in. Log in. The installation will go on. At some point, you will again be asked to authenticate. Only that this time the authentication does not crash.
// Probably typing the number does nothing, but I think its best you just exactly reproduce what I did.