The Case of the Unsigned Printer Drivers and .NET 3.5 Service Pack 1
Published Mar 15 2019 08:09 PM 467 Views
First published on TECHNET on Mar 06, 2009

Hello AskPerf – my name is Craig Marcho, and I am a Support Engineer on the Performance team in Texas.  Have you recently updated to .Net Framework 3.5 Service Pack 1?  Are you now seeing prompts when trying to install inbox printer drivers warning that the printers have not passed Windows Logo testing?  I recently worked on a customer incident during which we discovered that the .NET 3.5 Framework Service Pack 1 breaks the signing for inbox printer drivers.

The update includes the XPS Essentials pack, which installs an updated Unidrv.dll.  The Unidrv.dll binary provided in the update is not signed, which then causes all inbox printers to be unsigned.  There is a utility included with Windows, PRNDRVR.VBS, that can be used to install printer drivers.  This VBScript uses Windows Management Instrumentation (WMI) to install the printer drivers.  However, WMI does not allow the installation of unsigned driver files.  As a result, the installation will fail since the drivers appear to be unsigned.  Additionally, if you have a policy in place that prevents the installation of unsigned drivers, this will also keep you from being able to install any inbox printer drivers.  If you’re curious, here’s how you can reproduce this issue:

  1. Install .NET Framework 3.5 Service Pack 1

  2. From a command prompt, run the following command to install an inbox printer: rundll32 printui.dll,PrintUIEntry /ia /m "HP LaserJet Series II" /f %windir%\inf\ntprint.inf

  3. You will notice the following dialog box:

You may also see a warning if you are using the Add Printer Wizard to install an inbox driver:

Rest assured – we do have a fix available. Microsoft KB Article 961118 provides download links to the hotfix for the different OS versions that resolves the issue.  With that, we’re at the end of our post.  Thanks for stopping by!

- Craig Marcho

Share this post :

Version history
Last update:
‎Mar 15 2019 08:09 PM
Updated by: