Error 39 Virtual USB Bus Error in Mastercam X7 2022: A Comprehensive Fix
Are you encountering the frustrating Error 39 Virtual USB Bus error while using Mastercam X7 2022? This issue can disrupt your workflow and hinder productivity. In this response, we will provide a step-by-step guide to resolve the Virtual USB Bus Error 39 in Mastercam X7 2022.
What is Error 39 Virtual USB Bus Error?
The Error 39 Virtual USB Bus error typically occurs when Mastercam X7 2022 fails to communicate with the USB dongle or license manager. This issue may arise due to a corrupted driver, outdated software, or a conflict with other system applications.
Causes of Error 39 Virtual USB Bus Error:
Step-by-Step Fix for Error 39 Virtual USB Bus Error:
Conclusion:
By following these steps, you should be able to resolve the Error 39 Virtual USB Bus error in Mastercam X7 2022. If the issue persists, it is recommended to contact Mastercam support or a qualified technical expert for further assistance.
Additional Tips:
Title: The Ghost in the Bus
Arjun hated error codes. Not because they were complicated, but because they were liars. Error 39 on his Mastercam X72022 workstation read: “Windows cannot load the device driver for this hardware. The driver may be corrupted or missing.”
But Arjun knew the driver was fine. He’d reinstalled it eleven times.
The problem was the Virtual USB Bus. Mastercam’s new X72022 update required a hypervisor-level USB bridge to talk to his five-axis milling machine. It created a “ghost bus”—a fake USB highway inside the RAM—to shave microseconds off toolpath calculations. And tonight, that ghost had a flat tire.
It started during a 3D HST toolpath simulation. The screen froze, then vomited yellow triangles. Then: Code 39.
Arjun rubbed his eyes. The prototype impeller for the Mars coolant pump was due in nine hours. Without the virtual bus, Mastercam couldn’t see the machine’s hardware dongle. No dongle, no G-code.
He tried the usual exorcisms:
At 2:17 AM, Arjun opened Regedit—the forbidden forest. He navigated to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB\VID_0000&PID_0002\Device Parameters
There it was. A stray UpperFilters key with a value that wasn’t a driver. It was a timestamp: 2022-01-01T00:00:00Z. Someone at Mastercam, likely hungover on New Year’s Eve 2021, had hard-coded a filter that expired exactly at midnight, January 1st, 2026.
It wasn’t a driver problem. It was a calendar bomb.
Arjun deleted the UpperFilters key. He deleted the companion LowerFilters key for good measure. Then he opened Device Manager, right-clicked the “Mastercam X72022 Virtual USB Bus,” and selected Update Driver → Browse → Let me pick → Generic USB Hub.
Windows hiccupped. The yellow triangle turned into a green plug icon.
He launched Mastercam. The dongle light blinked. The toolpath regenerated. mastercam x72022 virtual usb bus error 39 fix
At 2:43 AM, the five-axis spindle whirred to life. The impeller began to take shape from a block of 6061 aluminum.
Arjun saved the registry fix as a .reg file and named it: NoMoreGhosts.reg
Then he wrote a single sticky note for the morning shift: “If Error 39 returns, delete UpperFilters. Also, check your CMOS battery. Time bombs love dead clocks.”
The virtual bus ran clean for the next three years. But Arjun never trusted a virtual USB port again. A ghost highway is still a highway—and every highway has a hidden off-ramp.
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)
The most common cause for Error 39 on Windows 10 and 11 is the Core Isolation security feature, which prevents many virtual USB drivers from loading. Open the Start menu and search for Windows Security. Navigate to Device security on the left-hand sidebar. Under Core isolation, click on Core isolation details. Switch the Memory integrity toggle to Off. Restart your computer for the changes to take effect. Secondary Fix: Registry Editor (Remove Filters)
If disabling Core Isolation doesn't work, corrupted registry "filters" might be blocking the driver. Press Windows + R, type regedit, and hit Enter.
Navigate to the following path:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C465-11CF-8056-444553540000
In the right pane, look for entries named UpperFilters and LowerFilters. Right-click and Delete both (if they exist). Restart your PC. Alternative Troubleshooting Mastercam X7-2022 Virtual Usb Bus Error 39 - Google Groups
The "Code 39" error for the Virtual USB Bus (often associated with
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)
: This is the most common cause on Windows 10 and 11. Newer Windows security features block older virtual USB drivers. Windows Settings Update & Security Privacy & security in Win 11). Windows Security Device Security Core isolation details and toggle Memory integrity your computer. Registry Modification (Hypervisor Enforced Code Integrity)
: If you cannot toggle Memory Integrity in settings, you can disable it via the Registry Editor. , and hit Enter. Navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity Delete Registry UpperFilters/LowerFilters
: Corruption in these keys can prevent USB drivers from loading.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C465-11CF-8056-444553540000 In the right pane, find UpperFilters LowerFilters , right-click, and select your system. Additional Troubleshooting Mastercam X7-2022 Virtual Usb Bus Error 39 - Google Groups
The "Virtual USB Bus Error 39" in Mastercam (typically appearing for older versions like X7 or when using virtual licensing/HASP tools on modern Windows) generally indicates that Windows has blocked a driver from loading because it doesn't meet security standards or has a corrupted registry entry .
The most effective fixes involve disabling Windows Core Isolation or cleaning the Registry. 1. Disable Memory Integrity (Most Likely Fix)
Modern Windows security features like Core Isolation (Memory Integrity) often block the older "MultiKey" or virtual USB bus drivers used by legacy software because they are not digitally signed to modern standards .
Action: Go to Windows Security > Device Security > Core Isolation details. Step: Toggle Memory Integrity to Off .
Restart: You must restart your PC for this to take effect. This is the primary reason why drivers that worked on Windows 7 fail on Windows 10/11 . 2. Remove Corrupted Registry Filters Error 39 Virtual USB Bus Error in Mastercam
If Windows still cannot load the driver after disabling security features, "UpperFilters" or "LowerFilters" entries in the registry may be blocking the USB class .
Registry Path: Navigate to:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C465-11CF-8056-444553540000 .
Action: In the right-hand pane, look for UpperFilters or LowerFilters. If they exist, right-click and Delete them .
Warning: Back up your registry before making changes. After deleting these, restart your computer to force Windows to re-enumerate the USB stack . 3. Reinstall Virtual USB Bus Drivers
If the above steps fail, the driver file itself may be "Bad Image" or improperly registered. How to Fix USB Error Code 39 In Windows 10/8/7 [Tutorial]
After deleting the value, close the Registry Editor and restart the computer to see if the issue is resolved. YouTube·MDTechVideos
The Virtual USB Bus Error 39 in Mastercam (spanning versions from X7 to 2022) typically indicates that Windows cannot load the virtual device driver, often flagging it as corrupted or missing. This issue is frequently caused by modern Windows security features like Core Isolation or residual registry filters that block the driver from initializing correctly. Primary Fix: Disable Core Isolation (Memory Integrity)
Most modern Windows 10 and 11 systems include a feature called "Memory Integrity" that prevents unsigned or older drivers from loading. Disabling this is often the most effective solution. Windows 10/11 Steps: Open the Start menu and type "Windows Security". Navigate to Device security on the left sidebar. Click on Core isolation details. Toggle the Memory integrity switch to Off. Restart your computer to apply the changes. Secondary Fix: Registry Editor (Upper and Lower Filters)
If disabling Core Isolation doesn't work, specific registry entries known as "UpperFilters" or "LowerFilters" might be corrupting the USB stack. Press Win + R, type regedit, and hit Enter.
Navigate to the following path:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\36FC9E60-C467-11CF-8056-444553540000
In the right-hand pane, look for UpperFilters or LowerFilters. Right-click them and select Delete. Restart your PC. Alternative Troubleshooting Steps
If the error persists, consider these hardware and driver-specific actions:
The Virtual USB Bus Error 39 in Mastercam versions from X7 through 2022 is typically caused by a Windows security feature called Core Isolation (Memory Integrity), which prevents unsigned or older drivers from loading. Primary Fix: Disable Memory Integrity
This is the most common solution for modern Windows 10 and 11 systems where the driver is blocked by security protocols.
Open Windows Security: Search for "Windows Security" in your Start menu.
Navigate to Device Security: Select the Device security tab on the left-hand menu.
Core Isolation Details: Click the link for Core isolation details.
Toggle Memory Integrity: Switch the Memory integrity setting to Off.
Restart: Reboot your computer to apply the changes. The driver should now load without Error 39. Secondary Fix: Windows Registry (HVCI Disable)
If the toggle is greyed out or does not resolve the issue, you can disable it via the Registry Editor.
Path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity Action: Set the Enabled DWORD value to 0. Restart: Reboot your PC after closing the editor. Advanced Troubleshooting Outdated or corrupted Virtual USB Bus driver Incompatible
If the error persists after disabling Core Isolation, try these additional methods: How to Fix USB Error Code 39 In Windows 10/8/7 [Tutorial]
To fix the Virtual USB Bus Error 39 in Mastercam (X7 through 2022 versions), you typically need to
address driver integrity issues caused by Windows security features or corrupted registry entries
The most common solution for modern Windows systems (10/11) is disabling Memory Integrity
, which often blocks virtual USB drivers used for licensing. Matsusada Precision 1. Disable Core Isolation (Memory Integrity)
Windows security can block the virtual driver from loading, resulting in Error 39. Windows Security (search for it in the Start menu). Device security Core isolation details Memory integrity
your computer and check the Device Manager to see if the error is gone. 2. Remove "UpperFilters" and "LowerFilters" in Registry
If disabling security doesn't work, corrupted registry values may be preventing the driver from loading. , and press Enter. Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\ Find the folder: 36FC9E60-C465-11CF-8056-444553540000 In the right pane, look for UpperFilters LowerFilters . Right-click and your computer. 3. Reinstall HASP Drivers
Corrupted drivers are a frequent cause. A clean reinstall is often necessary. How to Fix USB Error Code 39 In Windows 10/8/7 [Tutorial]
For nearly a decade, users of Mastercam—from X7 to the 2022 release—have encountered a baffling licensing error:
"Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)"
This appears in Device Manager under System devices as a broken entry named Virtual USB Bus. The error prevents the HASP (Hardware Against Software Piracy) or NetHASP license dongle from being recognized, rendering Mastercam unusable.
Despite appearing driver-related, Error 39 is rarely a true driver corruption issue. Instead, it stems from Windows driver signing enforcement, conflicting kernel drivers, or registry permission inheritance breaks—often triggered by Windows 10/11 feature updates, security patches, or third-party USB filtering software.
This feature provides a systematic, field-tested guide to diagnosing and eliminating Error 39 across Mastercam versions X7 through 2022, on Windows 10 and 11 (64-bit only).
Last Updated: October 2025
Applies to: Mastercam X7, X8, X9, 2021, 2022 (and legacy versions using NetHASP/Codemeter emulation)
Once fixed, you can avoid recurrence with these best practices:
Exclude Mastercam folders from Antivirus:
C:\Program Files\Mastercam 2022\C:\Windows\System32\drivers\hasplms.sysC:\ProgramData\SafeNet Sentinel\Never force-shut down Mastercam. Always exit cleanly. Hard crashes can corrupt the virtual bus registry state.
Use a powered USB hub. Voltage fluctuations on motherboard USB ports can cause the virtual bus to disconnect improperly.
Keep Sentinel drivers updated. Thales releases updates quarterly. Do not rely on old Mastercam installers.
This error became widespread for three main reasons:
Haspnt.sys or hardlock.sys files that the Virtual USB Bus depends on.Important Distinction:
- Error 39 (Virtual USB Bus) → Problem with the driver itself or its registry keys.
- Error 10 (Device cannot start) → Usually a USB port power or physical HASP issue.
- No error, but Mastercam says "No License Found" → HASP driver is working, but the license file is missing.