Mastercam relies on Aladdin/Thales Sentinel drivers. An outdated or corrupt sentinel driver triggers the virtual bus error. Open > Programs and Features . Uninstall Sentinel Runtime or HASP Driver .
Moving toward Mastercam’s (standard in newer versions), which eliminates the need for a USB bus driver entirely. To help you get back to programming, let me know: Are you using a physical dongle or a software emulator ? Which Windows version (10 or 11) are you currently on? Did this error appear after a Windows Update ?
Standard updates may fail if files are corrupted. A full reinstall is recommended.
"Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)" mastercam x72022 virtual usb bus error 39 updated
The most common cause for Error 39 in recent Windows updates is a security feature called (part of Core Isolation). This feature blocks drivers that it deems incompatible or unverified, which frequently includes virtual USB bus drivers used by older software. How to fix it: Open the Start Menu and search for Windows Security . Go to Device Security on the left-hand sidebar. Click on Core isolation details . Toggle Memory integrity to Off . Restart your computer to apply the changes. 2. Delete Registry UpperFilters and LowerFilters
To confirm it's a Code 39 driver issue, follow these steps:
Once completed, install it again by running: haspdinst.exe -i Verifying the Solution in Device Manager Mastercam relies on Aladdin/Thales Sentinel drivers
Windows Update from late 2021–2023 intentionally blocks vulnerable drivers used by virtual USB bus emulators (like HASP/hardlock clones). Error 39 means “driver corrupted or missing” — Windows disables it because the driver is unsigned or flagged as incompatible .
In simple terms, Code 39 indicates that Windows has recognized the "Virtual USB Bus Enumerator" device, but it has found a critical problem with its driver, preventing it from being loaded. The message generally points to one of three underlying issues:
Do not proceed to advanced fixes until you verify these three things: Uninstall Sentinel Runtime or HASP Driver
Many Mastercam installations use a virtual USB bus (like MultiKey) to manage the HASP/LDK license. Older versions of these virtual drivers are frequently flagged as incompatible by newer Windows updates. Step-by-Step Fixes (Updated for 2024–2025) 1. Disable Core Isolation (Recommended Fix)
If you must keep the original virtual USB driver:
Once you have resolved the error, take proactive steps to prevent it from recurring.
If the driver remains corrupted (Code 39), you may need to clear "UpperFilters" or "LowerFilters" that are blocking the USB class.