C# – Reference error with Fluent NHibernate 1.0 RTM and Visual Studio 2010 beta 2

I just had the same problem myself after configuring TFS Build service 2008 to use MSBuild 4.0. Everything worked before converting the projects, after then conversion to 2010 format and the switch to MSBuild 4 suddenly it couldn't find the 1.0.61025.0 AJAX libraries.

It turned out there was a registry key missing that pointed to the install location of MS Ajax extensions.

On my dev box the key that should be located at (64-bit OS)

HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\.NETFramework\v2.0.50727\AssemblyFoldersEx\ASP.NET AJAX Extensions

was instead placed in HKEY_CURRENT_USER. (32-bit OS: remove the Wow6432Node part)

On the build server the key was missing completely (none of the locally present user profiles had it in its registry hive).

The default value of this key should point to the MS Ajax Extensions installation directory, which in my case is

C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions\v1.0.61025

After recreating the key on the build server, our solution builds successfully under MSBuild 4.

It remains a mystery to me why it built successfully until now (under MSBuild 3.5). Perhaps the assembly search algorithm changed slightly and is now more restrictive.

Hope that helps.

Step1: Unload the referencing project targeting .NET 2.0

Step2: Right click the unloaded project and select edit from context menu

Step3: Add <SpecificVersion>true</SpecificVersion> to the reference. Below is a sample from my repro solution:

<ProjectReference Include="..\HighFX\HighFX.csproj">
  <Project>{8DD71CAF-BEF7-40ED-9DD0-25033CD8009D}</Project>
  <Name>HighFX</Name>
  <SpecificVersion>true</SpecificVersion>
</ProjectReference>

Step4: Reload the project.

Now your should be able to build within the Visual Studio 2010, there could still be a warning as below, but the build can be successful.

Source: http://social.msdn.microsoft.com/Forums/en-US/msbuild/thread/dfadfb34-5328-4c53-8274-931c6ae00836