Windows 10 and 11 have a security feature called that prevents "unsigned" or older drivers from loading. This is the #1 cause of Error 39 for Mastercam virtual bus drivers. Open Windows Security (search for it in the Start menu). Go to Device Security > Core isolation details . Toggle Memory integrity to Off .
In the context of Mastercam (ranging from legacy versions like X7 up to version 2022), the software relies on a USB hardware key (dongle) or an emulator to verify the software license. When you see this error, it is usually triggered by one of the following factors:
Mastercam, a leading Computer-Aided Manufacturing (CAM) software, relies on Sentinel (Hasp) security dongles for license management. These dongles communicate with the host machine via a proprietary "Virtual USB Bus" driver. "Error 39" is a Windows Device Manager error code that translates to: "Windows cannot load the device driver for this hardware. The driver may be corrupted or missing." Mastercam X7-2022 Virtual Usb Bus Error 39
Download the latest from the official Thales/Gemalto website. Extract the files to your C:\ drive. Open Command Prompt as an Administrator.
| Factor | Impact | |--------|--------| | Windows 10/11 security hardening | Driver signature enforcement is stricter after 2020. | | Lack of emulator updates | Most emulators were last updated for Mastercam 2018/2019. | | No official support | Mastercam will not help; error is from a non‑authentic setup. | | Community fixes are fragile | Solutions often break after a Windows update. | Windows 10 and 11 have a security feature
Restart your computer. A "Test Mode" watermark will appear in the bottom right corner of your screen, allowing the driver to load.
Error 39 occurs within the Microsoft Support. It generally means: Go to Device Security > Core isolation details
Upon reboot, press or F7 to select Disable driver signature enforcement . Permanent Deactivation (Advanced)
If your IT department forces Memory Integrity ON:
🛡️ Disabling Core Isolation reduces a layer of protection against malware. Only do this if you trust your local network and the drivers you are installing. If you'd like, I can help you: Find the latest official drivers for your specific version.