Sony Z3 can't transfer files by USB and isn't recognised by PC after update to 6.0.1
This is bizarre. I connected the phone via a different USB socket on the computer (same cable), and this time it worked fine, in fact better than before:


The Sony icon appeared without needing to "install" anything, and accesses both internal and SD memory like before
The "Install software" Sony message pops up on the phone like before now
The missing persistent notification on the phone appears: 


  USB for file transfer Touch for more options



I wasn't aware of the computer having different types of USB socket, but it seems like maybe there are some types of USB socket that an Android 6 phone will think work but actually don't?

I thought it might maybe have been a driver install thing, but the "bad" USB socket still doesn't work even after successfully using the connection to the "good" socket.



To add to the mystery, I have actually used this "bad" USB socket on this computer with this phone before, mere days before the Android update. Somehow the USB socket appears to compatible with Android 5 but not Android 6?

The "bad" USB socket also has no problem working with USB pen drives.

If anyone happens to know how I can find out what the technical difference between the two identical-looking USB sockets on my PC is, please comment!