There is no single “assist_button_driver.exe.” Instead, the button’s functionality depends on two software components:
So, when people say “Assist Button driver,” they generally mean the SFEP driver + VAIO Event Service + VAIO Care.
You have a conflicting shell handler. Run regedit, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Sony\VAIO Assist Button, and verify the correct path to VAIO Care. sony vaio assist button driver download link
If you upgraded your VAIO to Windows 10 or 11 from Windows 7 or 8, the original drivers often break. Sony released a specific "VAIO Care" package for newer operating systems.
The Download Link: 👉 VAIO Care for Windows 10/11 (Microsoft Store) (Note: This link works if the Microsoft Store app is active on your PC). There is no single “assist_button_driver
Alternative Fix for Win 10/11: If the button still does not work after installing the app above, you need to force-install the drivers in "Compatibility Mode."
If you are having trouble finding drivers manually, Sony created an automated tool. So, when people say “Assist Button driver,” they
The Download Link: 👉 VAIO Update Software
The website vaio-drivers.com (not affiliated with Sony) maintains a massive archive of original Sony drivers. For the Assist Button, search for:
Warning: Always scan any downloaded file with Windows Defender or VirusTotal. Do not use “driver updater” executables from unknown sources.