Mastercam X72022 Virtual Usb Bus Error 39 Fix May 2026

Feature: Resolving the Infamous "Error 39" in Mastercam (Versions X7 through 2022)

Introduction

For nearly a decade, users of Mastercam—from X7 to the 2022 release—have encountered a baffling licensing error:

Fix 7: Enable Test Mode (Permanent Signature Bypass)

If you don’t want to disable Secure Boot or reboot twice daily, use Test Mode. mastercam x72022 virtual usb bus error 39 fix

To fix the Virtual USB Bus Error 39 for Mastercam (versions X7 through 2022), you typically need to address security features in modern Windows versions that block certain virtual drivers. This error indicates that Windows cannot load the device driver because it is either corrupted, missing, or blocked. Primary Fix: Disable Core Isolation (Memory Integrity) Feature: Resolving the Infamous "Error 39" in Mastercam

  1. Press Win + R, type regedit, and hit Enter.
  2. Navigate to the following path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\4d36e965-e325-11ce-bfc1-08002be10318
  3. Identify the Key: This is the generic GUID for DVD/CD-ROM drives, but if you are dealing with a Virtual USB Bus, you may need to check: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C465-11CF-8056-444553540000 (This is the USB class key).
  4. Fix the Upper/Lower Filters:

    The Virtual USB Bus Error 39 in Mastercam versions X7 through 2022 typically indicates that Windows cannot load the device driver for the virtual HASP or dongle emulator, often due to a driver being corrupted, missing, or blocked by modern security features. The primary resolution involves disabling Core Isolation (Memory Integrity) in Windows Security or removing specific Registry filters that interfere with driver loading. Primary Cause: Windows Core Isolation vusbbus

    1. Close Mastercam and any licensing apps.
    2. Open Device Manager (Windows + X → Device Manager).
    3. Under "Universal Serial Bus controllers" and "Non-Plug and Play Drivers", locate entries named like: