Error 39 is a Windows operating system error (CM_PROB_DRIVER_FAILED_LOAD). It occurs when:
In the context of Mastercam’s Virtual USB Bus (used by cracked or old-license emulators as well as legitimate network license managers), the driver file is typically vusbbus.sys or multikey.sys. Windows now treats these as security risks, responding with Code 39.
Note: This article addresses technical troubleshooting for legacy systems. Ensure you own a valid Mastercam license. Using cracked software violates copyright laws. This guide is for repairing legitimate installations where the Virtual USB Bus is part of an official NetHASP setup.
The fix lasted 14 months until a Windows security update rewrote the USB class driver again. By then, Marcus had finally migrated to Mastercam 2024, but he kept an air-gapped Windows 10 LTSC machine with the hacked driver—just in case.
Error 39 remains a cautionary tale: Virtual USB buses are fragile illusions. When the OS changes the rules of reality, even a perfectly good dongle becomes a ghost. And sometimes, to fix it, you have to become a ghost yourself—editing registries, forging signatures, and whispering to the kernel in its own dark language.
Final technical summary for those who just want the fix:
| Step | Action |
|------|--------|
| 1 | Disable Secure Boot (temporarily) |
| 2 | Uninstall hidden "Virtual USB Bus (HASP)" device with driver deletion |
| 3 | Block automatic reinstall via pnputil /disable-device |
| 4 | Modify HASP INF to add LowerFilters key |
| 5 | Self-sign INF and add to Trusted Publishers |
| 6 | Registry: SkipDriverError39Check = 1 under the device instance |
| 7 | Re-enable Secure Boot (if stable) |
Warning: This is a deep hack. It works for Mastercam X7 (and similar older HASP-protected software) on Windows 10 22H2 and early Windows 11 builds. Not for production environments without rigorous testing.
The Virtual USB Bus Error 39 in Mastercam (versions X7 through 2022) typically occurs when Windows prevents a third-party driver, such as the MultiKey or HASP emulator, from loading due to security restrictions or registry corruption. Below are the standard methods to resolve this error: 1. Disable Core Isolation (Memory Integrity) mastercam+x72022+virtual+usb+bus+error+39+fixed
The most common cause of Error 39 on Windows 10 and 11 is the Core Isolation feature, which blocks drivers that don't meet specific security standards.
Open the Start menu, search for Windows Security, and open it. Go to Device security > Core isolation details. Toggle Memory integrity to Off. Restart your computer to apply the changes. 2. Remove Registry UpperFilters and LowerFilters
Corrupted registry entries for USB classes can cause driver load failures. How to Fix USB Error Code 39 In Windows 10/8/7 [Tutorial]
Title: How I Fixed the Mastercam + X7 2022 "Virtual USB Bus Error 39" (Step-by-Step) Tags: Mastercam, X7 2022, Error 39, Virtual USB, NetHASP, CAD/CAM Fix
The Frustration is Real
There is nothing worse than sitting down to hit a deadline, firing up Mastercam (X7 or 2022), and being greeted by the dreaded Error 39:
"Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)"
If you are using a Virtual USB Bus emulator for your NetHASP (often for legacy licensing or hardware replacement), this error effectively bricks your software. Device Manager shows that yellow exclamation mark, and Mastercam refuses to see the license. Error 39 is a Windows operating system error
After two days of trial and error, I finally fixed it. Here is exactly how.
Download Sentinel HASP 7.52 (a 2019 version, not the latest 8.x). Extract the driver INF. Inside haspvbus.inf, locate:
AddReg = HASP_VBus_AddReg.NT
Add this line to force legacy PnP handling:
HKR,, LowerFilters, 0x00010008, "haspvfilter"
Then sign the modified INF using a self-signed certificate and add it to the Windows Trusted Publishers store (requires disabling Secure Boot temporarily).
It was a humid Tuesday night in April 2022. A small but mighty aerospace prototyping shop in Dayton, Ohio, had just rolled out a mandatory Windows 11 update across its CAM workstations. The lead programmer, Marcus, watched the progress bar hit 100%, rebooted his Dell Precision, and launched Mastercam X7.
The splash screen hung. Then, the error:
"No license found. Error Code: 39 - Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Virtual USB Bus)"
Marcus’s stomach dropped. X7 was ancient—released in 2013. But it was their ancient. It ran a legacy post-processor for a 5-axis DMG Mori that cost more than his house. The post-processor had been customized over eight years, line by arcane line. Upgrading Mastercam meant a $25,000 software re-certification and three months of downtime. In the context of Mastercam’s Virtual USB Bus
The culprit? Error 39.
If nothing else works, remove all traces of HASP/Virtual USB Bus using SafeNet’s official removal tool.
Critical: After this process, reboot twice before testing Mastercam.
Replace the virtual bus entirely with an older version of the HASP driver from 2016:
Do not jump straight into registry editing. First, perform these quick checks:
If these steps do not resolve Error 39, move to the advanced fixes below.
Follow the ordered recovery sequence above; if the issue persists after reinstalling the correct vendor runtime and repairing system files, collect the requested logs and contact the dongle vendor or Mastercam support.
(Invoking related search suggestions now.)