Now you know exactly why that happens and how to fix it.
Have you experienced the infamous counterfeit driver lockout? Or do you still use FTDI chips in new projects? Let me know in the comments below.
In this post, we’ll tear down what ftdibus.sys really is, how it works, common issues, security considerations, and best practices for managing it. ftdibus.sys is a kernel-mode driver file developed by Future Technology Devices International (FTDI) , a Scottish semiconductor company famous for its USB-to-serial converter chips (the FT232x series being the most popular). ftdibus sys
In simple terms, ftdibus.sys allows Windows to communicate with FTDI chips over USB. When you plug in a device containing an FTDI chip, Windows loads this driver, which creates a virtual COM port (e.g., COM3 ). Your terminal software (PuTTY, Tera Term, etc.) then uses that COM port to send and receive serial data.
Found this useful? Share it with a fellow engineer or sysadmin. Now you know exactly why that happens and how to fix it
C:\Windows\System32\drivers\ftdibus.sys
If you’ve ever worked with microcontrollers (Arduino, ESP32), legacy industrial equipment, GPS modules, or 3D printers, you have almost certainly encountered ftdibus.sys —even if you didn’t know it by name. This unassuming system file is a critical component of the Windows ecosystem, acting as the software bridge between your USB port and the virtual COM port that makes so much of modern hacking, debugging, and automation possible. Let me know in the comments below
Published: April 14, 2026 | Reading time: 7 minutes