Error When Installing Visual Studio 2005 SP1: "The installation source for this product is not available."

Published 15 January 07 09:26 PM | Scott Mitchell

I installed Visual Studio 2005 Service Pack 1 today on my main development box (Windows 2003 Server) and ran into the following error: “The installation source for this product is not available. Verify that the source exists and that you can access it.” In particular, I received the following error dialog box:

Some Googling turned up a fix for a very common error message when installing SP1 - “Error 1718. File FileName was rejected by digital signature policy” - but it took a bit more searching before I found this bug report in which user rlasker provided the following helpful comment:

I had this issue. When I looked in the event log I found this:

Event Type: Error
Event Source: MsiInstaller
Event Category: None
Event ID: 1008
Date: 12/18/2006
Time: 12:18:31 PM

The installation of C:\DOCUME~1\...\LOCALS~1\Temp\ZNWA0\VS80sp1-KB926601-X86-ENU.msp is not permitted due to an error in software restriction policy processing. The object cannot be trusted.

I followed the instructions at this link:

And it no longer gave me the error descibed above.

Looking in my Event Log I found the same details and dutifully applied the workaround described at the KB ( These steps remedied the problem, and after rebooting I was able to successfully install SP1. Hopefully this post makes it to the first page of Google's results so future developers running into the same problem who are Googling the error message can more quickly find a fix.

For more VS 2005 SP1 info, see:

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