Mastercam users transitioning from older versions like X7 to modern releases like 2022 often encounter the frustrating "Virtual USB Bus Error 39". This error typically presents as a yellow exclamation mark in the Device Manager next to the "Virtual USB MultiKey" or "Sentinel" driver, preventing the software from detecting the necessary security dongle.
The core issue is that Windows 10 and 11 have stricter security protocols—specifically Core Isolation (Memory Integrity) and Driver Signature Enforcement—which block older virtual USB bus drivers from loading.
Here is the comprehensive guide to fixing Mastercam Virtual USB Bus Error 39. Phase 1: Disable Windows Core Isolation (Primary Fix)
Modern Windows security features can block third-party virtual drivers. This is the most common cause of Error 39.
Open Windows Security: Click the Start menu, type "Windows Security," and open it.
Navigate to Device Security: Select Device security on the left sidebar. Core Isolation Details: Click on Core isolation details.
Toggle Memory Integrity Off: Find the "Memory integrity" switch and turn it Off.
Restart Your PC: You must restart your computer for these changes to take effect. Phase 2: Disable Driver Signature Enforcement
If the error persists after disabling Core Isolation, Windows may still be blocking the driver because it isn't digitally signed for the current OS version. Hold the Shift key and click Restart from the Start menu.
Go to Troubleshoot > Advanced options > Startup Settings > Restart.
After the PC restarts, press 7 or F7 to select "Disable driver signature enforcement".
Once Windows boots, check the Device Manager to see if the Virtual USB Bus is now active. Phase 3: Registry Editor Fix (Removing UpperFilters)
Corrupted registry entries can prevent the USB bus driver from initializing correctly. How to Fix USB Driver Error Code 39 - Matsusada Precision
The Mastercam Virtual USB Bus Error 39 has frustrated machinists and programmers for nearly a decade. However, as we have demonstrated, the error is almost always repairable without reinstalling Windows or buying a new PC.
To recap your battle plan:
vusbbus.sys (bypasses corruption).hasphl.exe nuclear cleanup.After applying these steps, Mastercam X7 through 2022 will finally recognize the Virtual USB Bus, Error 39 will vanish, and your CAD/CAM workflow can resume.
If you are still stuck, post your Windows build number (run winver) and the exact text of the error in the comments below. The community has solved hundreds of these cases—yours will be next.
Disclaimer: This article is for educational and troubleshooting purposes only. Unauthorized use of cracked software or circumvention of licensing mechanisms is illegal. Always use legitimate Mastercam licenses provided by a certified reseller.
In Mastercam (X7 through 2022 versions), Virtual USB Bus Error 39
is a common driver-related issue that prevents the software from verifying its hardware security key (HASP)
. This error typically indicates that Windows cannot load the device driver because it is either corrupted, missing, or blocked by modern security features. Core Causes Core Isolation (Memory Integrity):
This is the most frequent cause on Windows 10 and 11. This security feature blocks older drivers that don't meet modern memory safety standards. Corrupt Registry Entries:
Invalid "UpperFilters" or "LowerFilters" in the Windows Registry can prevent the USB bus from communicating with the driver. Driver Incompatibility:
Legacy Mastercam versions (like X7) use older Virtual USB MultiKey drivers that are often flagged as unsigned or incompatible by newer Windows updates. Step-by-Step Fixes 1. Disable Core Isolation (Most Effective)
Since many Mastercam drivers are older, disabling this Windows security feature often resolves the block immediately. Windows Security via the Start menu. Navigate to Device security Core isolation details Memory integrity your computer for changes to take effect. 2. Modify the Windows Registry
If disabling Core Isolation fails, you may need to clear corrupted filter entries. Back up your registry before proceeding. , and run as Administrator. Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\ Locate the USB class folder: 36FC9E60-C465-11CF-8056-444553540000 In the right pane, find UpperFilters , right-click it, and select 3. Reinstall Virtual USB MultiKey Drivers
For older Mastercam versions (X7–X9), the virtual bus itself may need a "clean" reinstallation. Device Manager
and find the "Virtual USB MultiKey" with the yellow exclamation mark. Right-click and select Uninstall device remove.bat
(or similar) file from your Mastercam installation folder to clear old driver fragments. install.bat mastercam+x72022+virtual+usb+bus+error+39+fixed
as an Administrator to reinstall the updated 64-bit drivers. Advanced Troubleshooting
If the steps above do not work, consider these alternative solutions reported by the community: Mastercam X7-2022 Virtual Usb Bus Error 39 - Google Groups 24 Jul 2024 —
Virtual USB Bus Error 39 in Mastercam versions (including X7 through 2022)
typically occurs because Windows security features or registry conflicts prevent the emulator drivers from loading properly Matsusada Precision Primary Fix: Disable Memory Integrity (Core Isolation)
Modern Windows versions (10 and 11) include a security feature called Core Isolation
that often blocks virtual USB drivers used by older software emulators. Start Menu and search for Windows Security Navigate to Device security Core isolation details Toggle the Memory integrity your computer. Secondary Fix: Registry Filter Deletion
If the driver is flagged as corrupted despite being installed correctly, you may need to clear "UpperFilters" from the registry. , and run as Administrator Navigate to the following path:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C465-11CF-8056-444553540000 In the right pane, look for UpperFilters . Right-click and select your system. Driver Refresh Steps
If the error persists after the steps above, a clean driver install is necessary: Uninstall Existing Drivers Device Manager
, 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
: If you are using an unsigned emulator driver, you must boot Windows into Disable Driver Signature Enforcement mode to allow it to load. Reinstall Sentinel/HASP : Use the official Sentinel HASP LDK Runtime
to ensure the physical or base virtual components are current. Google Groups permanently? Mastercam X7-2022 Virtual Usb Bus Error 39 - Google Groups
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. Mastercam users transitioning from older versions like X7
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 "Code 39" error for the Mastercam Virtual USB Bus (often associated with MultiKey or HASP emulators) typically indicates that Windows cannot load the driver because it is either corrupted, missing, or blocked by security features. This issue is common in Windows 10 and 11 environments due to increased security around unsigned or third-party drivers. Primary Cause: Core Isolation (Memory Integrity)
The most frequent cause of Code 39 for virtual drivers in modern Windows is Core Isolation , specifically the Memory Integrity
setting. This feature prevents drivers that do not meet strict security standards from loading. Matsusada Precision How to Fix Windows Security from the Start menu. Navigate to Device Security Core isolation details Memory integrity Restart your computer to apply the changes. Matsusada Precision Alternative Solution: Registry Modification
If the error persists or you cannot access security settings, you can manually disable the integrity check via the Registry Editor. Registry Path
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity : Find the value and set it to Legacy Fix : Some users resolve Code 39 by deleting UpperFilters LowerFilters
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C465-11CF-8056-444553540000 if they exist. Driver Reinstallation Steps
It looks like you have provided a search query or a title for a technical fix regarding Mastercam X7 2022 and a specific Windows error.
Here is the information and solution based on that query:
Problem: You are trying to run Mastercam X7 (or a similar version) on Windows, but the software fails to launch or cannot find the SIM (license), displaying "Virtual USB Bus Error 39".
Cause: This error is caused by the Mastercam USB Emulator (the "virtual USB" driver used to simulate the hardware license key). Specifically, Error 39 in Windows Device Manager means that the driver installed correctly, but Windows cannot load the specific driver file (usually due to digital signature requirements or a corrupted registry entry).
If you just need the software to boot once: Quick troubleshooting commands