Problems opening driver in different user accounts


From CVB version 13.03.003 onwards we cannot open the in different windows user accounts.

You get the following message ‘Failed to load file’

You can only seem to access the driver file in the account CVB was installed. In both accounts though you can still view live camera’s through the CVB management console.

When we load the camera’s through our software we use the following function:

‘LoadImageFile’ and pass through the filepath “C:\Program Files (x86)\STEMMER IMAGING\Common Vision Blox\Drivers\”

this returns true in the one account and false in any other accounts. I have ensure all accounts have administrator rights.

Currently we are having to use version 13.03.002 (x86) as we do not have this problem.



I’ve just tested this on Win7 32 with CVB 13.03.003 and I can load the with one user account (using CVB Viewer application for testing purposes), then I close the application to free the driver, then I switch to another user account and load the again with CVB Viewer. Works just fine on my machine.

Do you have installed CVB for all users?

Do you make sure to free/unload the driver with one account when switching to another account?

1 Like

Hi @Austin

The installers for 13.03.002 and 13.03.003 (and in fact all the other versions since set the access rights for the %CVBDATA% folder for read/write for everyone. That folder is usually located in C:\ProgramData\STEMMER IMAGING\Common Vision Blox. You might want to check/verify that your 2nd user has at least read permission on that folder and all its sub-directories.

Another thing that might have been compromised for your 2nd user are the environment variables - if these are not set properly, opening the is likely to fail. You’ll need

  • CVB

All these need to be set identially to the user account for which loading the vin works (the installer sets these for all users, but they might have been overwritten individually).

And finally, as @Frank pointed out, you cannot open a device that has already been opened by another user - trying this would also look like a failure to load the

I hope these hints help. Generally, there’s nothing we made differently between the 13.03.002 and the 13.03.003 installer (just a few changes to the fileset; the installer projects are identical between patch releases - otherwise we would jeopardise the upgrade-capabilities…).

Hi @illusive, @Frank ,

We have setup a fresh 64bit Windows 10 machine, with only the default applications installed with windows and CVB 13.04.000 (32bit, runtime only).

The steps you advised previously have been checked and looks ok, but we are still getting the ‘Failed to open’ when trying to load the driver via the CVB viewer when logged into the second, non-admin, user account…but not all the time, this is a ‘random’ fail, generally after a power cycle of the PC and camera.

One thing i did notice, is when it does fail to open, we can fix it by opening the CVB Management console in the second non-admin account then closing it. The viewer is then happy to open the driver for a while, then will fail after a power cycle of the PC and camera.

I have uploaded an MP4 file showing this behavior. Link -

Any thoughts?