After installation, navigate to C:\Flashtool\drivers. Run Flashtool-drivers.exe. A list of Xperia models appears. Select:
Troubleshooting: On Windows 8/10/11, you must disable driver signature enforcement temporarily. Reboot your PC while pressing Shift, go to Troubleshoot > Advanced Options > Startup Settings, and select “Disable driver signature enforcement.” Sony Flashtool 0.9.18.6
Unplug the USB cable. Press and hold the Power button for 3–5 seconds. The phone vibrates and boots to Sony logo. First boot takes up to 10 minutes. Set up your device as new. After installation, navigate to C:\Flashtool\drivers
Search for SonyFlashtool-0.9.18.6-windows.exe (or the Linux .jar version). Trusted sources include: Troubleshooting : On Windows 8/10/11, you must disable
Warning: Avoid random file-sharing sites. Verify the file size (approx 85 MB) and scan with antivirus.
Note: The official hosting site (androxyde.github.io) now serves newer versions. You can find 0.9.18.6 on reputable XDA Developers mirrors or archive.org.