msbuild - VSTS 2010 SGEN : error : Could not load file or assembly (Exception from HRESULT: 0x80131515)

Question

I am experiencing a strange issue with VS2010. We use TFS to build our API dlls and we used to reference them in our projects usign a mapped network drive that was fully trusted. We have been working like that for at least two years and everything worked perfectly.

Today, I converted a webapp to vs2010 and when I compile it in Release, it's giving me:

SGEN : error : Could not load file or assembly 'file:///L:ApiRelease API_20100521.1ReleaseCS.API.Exceptions.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)

The strange thing is that it's working when it's under the Debug profile...

I tried adding the

<runtime>
   <loadFromRemoteSources enabled="true" />
</runtime>

into app.config and still no luck (See http://social.msdn.microsoft.com/Forums/en/msbuild/thread/d12f6301-85bf-4b9e-8e34-a06398a60df0 and http://msdn.microsoft.com/en-us/library/dd409252(VS.100).aspx)

I am pretty sure that this issue is from visual studio or msbuild, as our code won't run from a network share when in prod because all the referenced dll's are copied into the bin folder.

If anyone has an solution (or just an idea for a search path) please let me know !

Edit : It turns out that it was working in Debug mode because generation of serialisation assemblies was turned Off. As the title say, it's really a SGEN problem since it is this utility that says that the path is not trusted...

Answer 1

I was able to fix this error by finding the assembly DLL in Windows Explorer, right clicking, choosing Properties, and then pressing the "unblock" button. The DLL has a stream that is marking it as an external file - and by clicking unblock you remove that designation.