I have this same problem. Sony Spain is telling me to use a software, Sony Xperia Companion, "to repair the software". That process will delete the internal memory bla bla bla, and if it doesn't work, I have to send my phone in for repairs.
This is absolutely unacceptable. MANY years ago (over 10), Samsung told me to reset the phone to factory when I complained about contacts not synchronizing well with the computer, and same thing HTC said when the a phone was working slow (it turns out the HTC One M7 can't handle Android encryption, but it works quite well four years later without encryption).
This is the EASY thing to say, which is a total hassle for users, and won't solve anything. Since most users are not willing to go through this process, then they can wash their hands and tell them it's their fault for not following their directions.
This is OBVIOUSLY a firmware problem. Solve it and push the update!
