Since the old driver is unsigned, you must allow it to load.
This is almost always caused by a Windows Update. An update can change system files or tighten security policies, which then causes the previously tolerated Virtual USB driver to be blocked. You may need to reapply the fix or disable driver signature enforcement as described below.
This is the most common cause on modern Windows systems, as Memory Integrity blocks unsigned drivers. mastercam+x72022+virtual+usb+bus+error+39+fixed
This guide explains why this error happens and provides step-by-step solutions to fix it. What Causes Error Code 39?
Security software isolating essential emulator DLLs or system files during a Windows update. Step-by-Step Solutions to Fix Error 39 Since the old driver is unsigned, you must allow it to load
Download the official, updated from the Mastercam or Thales support portal.
Once Windows boots up, reinstall your Mastercam virtual USB bus driver. You may need to reapply the fix or
Error Code 39 is primarily a driver signing and security conflict. It typically happens due to three main triggers:
, right-click the "Virtual USB Bus" (often under System Devices or Universal Serial Bus controllers) with the yellow exclamation mark, and select Uninstall device Driver Signature Enforcement
Windows 10 and 11 block drivers that aren't verified by Microsoft.
After 14 hours of forum-diving, Marcus found a cryptic post on a Russian CNC forum (translated):