virtualbox.org

After UPDATING any version of Oracle VM on a Windows Host you get the following error:

Failed to access the USB subsystem
Could not load the Host USB Proxy Service (VERR_FILE_NOT_FOUND).
The service might not be installed in the host computer.

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I've seen many fixes for this issue that just never worked for me.
Not finding a fix that actually worked for me, I began debugging the system and found the problem.
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The problem occurs when the "Oracle VM" USB drivers and registry entries are removed or corrupted on the HOST system.
Re-installing or Repairing the Oracle VM software does not fix the problem as the USB re-install procedure is not complete and fails without notice.

GOOD NEWS
You can fix the problem manually by modifying two INF files already installed on your HOST.

You can modify the files yourself, or
I have attached the modified files and instructions in a .zip file.

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=== DIY 3 Step Instructions ===
==========================

****STEP ONE****
Go to the folder: \Program Files\Oracle\VirtualBox\drivers\USB\filter
Right Click on the file: VBoxUSBMon.inf
and choose the option; OPEN
The file should open in your editor (default editor is: notepad.exe)
After the [Manufacturer] SECTION
add the following:

[DefaultInstall]
DefaultInstall.NT

Save the file and close the editor.
Right Click on the file again and choose: INSTALL

****STEP TWO****
Go to \Program Files\Oracle\VirtualBox\drivers\USB\device
Right Click on the file: VBoxUSB.inf
and choose the option; OPEN
The file should open in your editor (default editor is: notepad.exe)

After [SourceDisksNames] SECTION
add the following:

[DefaultInstall]
CopyFiles=VBoxUSB.Files.Ext
ORACLE.NTamd64

[DefaultInstall.Services]
Addservice = VBoxUSB, 0x00000002, VBoxUSB.AddService
VBoxUSB.AddService
VBoxUSB.AddReg

Save the file and close the editor.
Right Click on the file again and choose: INSTALL

****STEP THREE****
Reboot your computer.

That's it,
Your Windows HOST should now load the "Oracle VM" USB .sys files
which will create and mount the "USB subsystem" used by the VM Appliances.

I am retired and do not monitor this post or respond to inquiries.
Good Luck.

thanks a lot. works fine.
(W7 Ent 64bit; VB 4.2.6)

This also solved my issue, thanks.

For some reason, the USB driver installation information in the so-called windows 'Driver Store' showed the Oracle driver 'VBoxUSB.inf' as installed, but the necessary driver 'VBoxUSB.sys' dissapeared from directory 'C:\Program Files\Oracle\VirtualBox\drivers\USB\device'.
Manually re-installing this driver by right mouse click on the inf-file 'VBoxUSB.inf' and choosing 'Install' returned done/applied, but when looking the INF-log files (found in file 'C:\Windows\INF\setupapi.dev.log') showed 'already installed, so doing nothing'.

First I needed to remove the driver from the windows administrator, to allow re-install.
I used the program 'DriverStore Explorer v0.11.64' for this, since I had no idea how to do this with standard avaiable windows tools.

After this, I could retry to manual installation of by right mouse click on the inf-file 'VBoxUSB.inf' and choosing 'Install', but again it did not result in the file 'VBoxUSB.sys' in 'C:\windows\system32\drivers'. I checked the log files for INF installation ('C:\Windows\INF\setupapi.dev.log') and it did execute the installation and did not show 'already installed'.

At that time, I found your above fix (adding entries of 'DefaultInstall' to the inf-file) and retried manual install with right mouse click on the inf-file.
It gave a warning stating the hash was not matching anymore, which is due to changing the inf-file content, but executed and now the file 'VBoxUSB.sys' appeared in 'C:\windows\system32\drivers'.

After a reboot, I retried starting the guest and tried USB forwarding and it worked again.
As expected the windwos Device Manager on the host is showing the 'Virtual Box USB' device (hidden).