Unlocking Bootloader on Xperia Z3 compact

[petefoth]

I assume this is with a Windows Computer? (on macOS and Linux I don’t think you need drivers). If so I can’t be much help, as I don’t have a Windows machine.

One thing that has worked for others, if you don’t already have it, is installing Xperia Companion - see this post

Using flashtool

I think that what you are seeing means that adb cannot detect that a phone is connected. To check type ‘adb devices’. If it gives you no result, then either 1: your phone is not connected properly 2: you have not enabled USB debugging on your phone or 3: you don’t have the correct driver installed (assuming you are working on Windows). If it is 3: then I don’t know how you should proceed: I haven’t used Windows in many years. DOyou have Xperia Companion installed on your PC https://www.sony.co.…

I believe that Xperia Companion comes with whatever drivers you need. Good luck!