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Strong Name Validation failed when Debugging ASP.NET on IIS7

Ugh, since I installed a new machine I ran into this error message above earlier. That's a pretty omnious sounding error message which seems to hint at a mis-configuration during installation. The error occurs as soon as you try to debug a Web application against IIS 7...

As it turns out the problem is much simpler:

IIS 7 installs without Windows Authentication enabled. Without proper authentication Visual Studio can't effectively validate against IIS in order to get the appropriate rights to start the rather intrusive debugging process against IIS and so it fails.

The error message is a bit misleading and in fact my first thought was that during setup some assembly didn't get properly signed. I was already reaching for sn to start signing assemblies <g> or bypassing signing checks. Yuch.

Oddly the error message for this particular scenario has been changing over time. I have run into this before - with Win2003 server I believe although at the time the error message was even more out in left field.

To be fair though the help topic that pops in Orcas does point in the right direction if you read carefully through the Setting up for Debugging topic. Seems this particular issue will be common enough though that it should be at the top of the list.

Thankfully an easy one to fix.

I'll be at DevIntersection in Vegas this fall giving sessions on ASP.NET Core with Angular and Localization. Thinking of coming? Use discount code STRAHL and save a few bucks. If you do be sure to stop by and say hello!

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Posted in ASP.NET  IIS  Visual Studio  

The Voices of Reason


Edgardo Rossetto
August 21, 2007

# re: Strong Name Validation failed when Debugging ASP.NET on IIS7

I ran into the same problem. The "easy fix" is not so cool when you're trying to debug a WCF service that is not compatible with Windows Authentication (e.g it uses some other authentication scheme that's incompatible).


August 22, 2007

# re: Strong Name Validation failed when Debugging ASP.NET on IIS7

Hi Rick,

Completely off topic but... which tool do you use to generate the screenshots on your blog. The cut-out, jagged edges with shadowing look cool.


Rick Strahl
August 23, 2007

# re: Strong Name Validation failed when Debugging ASP.NET on IIS7

Mark, I use and absolutely love SnagIt. Especially since it can be automated with COM and so I've created a plug in for Live Writer (http://www.west-wind.com/tools/snagitlivewriterplugin.asp) as well as integrated with Help Builder. Easily one of the most used utilities I use.

Rod Weir
January 08, 2008

# re: Strong Name Validation failed when Debugging ASP.NET on IIS7

Yeah, I second SnagIt as the tool to use for screen shots. Worth every cent.

BTW, if you remove the 1 pixel black border from your ripped edge, it will look even better!

Best regards,


West Wind  © Rick Strahl, West Wind Technologies, 2005 - 2017