C:\Windows\SysWOW64\drivers\
A specific Windows Update, KB5004237 , is a known offender for breaking Mastercam's virtual USB drivers. Many users have reported that after their system automatically installed this update, their previously working Mastercam setup stopped functioning. The update revokes the trust in the digital certificates of several older drivers, including the ones used by the Mastercam virtual USB emulator. If your problems started immediately after a Windows update, this is likely the cause.
Check the box that says if prompted.
In the case of Mastercam's Virtual USB Bus, the most common triggers include:
drivers) in Mastercam typically indicates that Windows cannot load the driver because it is corrupted, missing, or blocked by security features. Microsoft Learn Primary Fixes for Error Code 39 Disable Core Isolation (Memory Integrity) mastercam x72022 virtual usb bus error 39 fix
Right-click the Start button and open .
Sometimes, Windows fails to automatically re-enable the driver. Open . Expand Universal Serial Bus controllers . If your problems started immediately after a Windows
This is only a temporary fix. The setting will revert to normal upon your next system restart. See Solution 5 for a more permanent resolution.