Issues flashing XPeria X

I can't see anything here to help solve my issue. When you say "Using the dialog windows and choosing WinUsb-device and ADB-device" I don't see anything like that at all. All I get is the standard dialog asking me where the drivers were unzipped to. In the other thread you linked to there's mention of an S1Boot Fastboot under USB devices. I don't have a USB devices in my Device Manager and the only S1Boot Fastboot is under Other Devices, but that one has the warning triangle. I think I'll get my Win 7 laptop and see if anything works from there.

Just tried Windows 7 and getting exactly the same from there. Windows can't find the S1Boot Fastboot driver even though I'm pointing it at the folder where it's unzipped. Still can't find these WinUsb-device and ADB-device either.

The problem (as far as I have understood) is that windows makes the fastboot an other device instead of a usb device, the driver that is supplied is not for an other device but for a usb device. You can find it using the file dialog. I will try to describe it completely because it costed me a lot of time to figure it out, using the question I mentioned earlier. Bear in mind that I already flashed my Xperia X (hurray!), so I can't reproduce it anymore with my laptops. Based on the description of Jolla:

2.4 Find the ‘S1Boot Fastboot’ device in the tree. If it is not correctly installed, it will show a warning sign.

2.5 Right-click it and choose ‘Update driver’

2.6 then ‘Browse my computer for driver software’,

2.7 Select “Let me pick from a list of available drives on my computer”

In this screen: (quote) instead of "have a disk ..." (which I initially tried without success) I tried the options in the table shown (I am not shure if that table was there at my first attempts). The table had two columns, a first column with two entries and a second column with three entries. From the first column I chose "WinUsb-device" and from the second column of the table I chose "ADB-device". I got a warning but decided to have the driver installed anyway and it worked, driver was installed and I could proceed after hours of trying! (unquote) (Maybe you have to uncheck the "show compatible hardware" first)

2.16 After this you should see “Windows has sucessfully updated your drivers” and you can click “Close” Fastboot is now a usbdevice without a warning sign. Now your device will be ready for unlocking and you can proceed with the next steps.

Windows 10 will install the drivers if driver signing enforement is off. You have to perform an advanced boot reboot and if you have bitlocker unlock the drive with the recovery key.