SGEN failure: An attempt was made to load an assembly with an incorrect format in VS2008

Question

I was able to find several similar questions asked and answered, but none of the answers or exact conditions applied to my situation.

1. I have a .NET 3.5 project being built for x64.
2. I also have an x64 mixed mode reference (also targeting .NET 3.5).
3. In Visual Studio 2008, I created a Web Reference which causes SGEN to execute during a Release build to create the helper DLL.

If I don't reference the mixed-mode DLL, this works fine. If I do reference the mixed mode DLL, I get this error (xxx is just a placeholder):

SGEN : error : An attempt was made to load an assembly with an incorrect format: C:\code\xxx\trunk\xxx\common\xxx\build\winx64\lib\xxx.dll.

This is the command being issued:

C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin\sgen.exe /assembly:C:\code\xxx\trunk\xxx\xxx\obj\x64\Release\xxx.dll /proxytypes /reference:..\common\xxx\build\winx64\lib\xxx.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.configuration.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Configuration.Install.dll /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.5\System.Core.dll" /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.EnterpriseServices.dll /reference:C:\Windows\assembly\GAC_MSIL\System.Management.Automation\1.0.0.0__31bf3856ad364e35\System.Management.Automation.dll /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0\System.Runtime.Serialization.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0\System.ServiceModel.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.5\System.Web.Extensions.dll" /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Web.Services.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll

Any ideas?

Answer 1

Have you tried changing Generate serialization assembly to Off, as suggested in this msdn post? In my case, that was the ticket.

Just go to your Project properties, and it's under Build.

Answer 2

This error also pops up on a build machine after installing MSBuild Toolset (for Visual Studio 2013). The problem is that only the 32bit version of sgen.exe is available by default.

The problem disappears after installing the latest Windows SDK which includes the 64Bit version of sgen.exe:

http://msdn.microsoft.com/en-us/windows/desktop/bg162891.aspx

On one agent (machine) I needed to install the older version as well:

http://msdn.microsoft.com/en-us/windows/desktop/hh852363.aspx

Answer 3

While turning serialization assembly off, will solve the problem, it is just workaround - in the end you'll pay for it with slower start up time. The problem is you have to call sgen.exe from x64 SDK (if you're targeting x64). If you're using msbuild, set correct path to sgen like this:

<MSBuild Projects="$(MSBuildProjectLocation)" Targets="Build"
    Properties="....
    SGenToolPath=C:\Program Files\Microsoft SDKs\Windows\v6.1\Bin\x64;" 
/>

Answer 4

This is an alternative to Ondrej's answer.

We just made the modification for our Release configuration in the project file (csproj) and set the SDK path to the x64 version:

  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    ...
    ...
    ...
    <GenerateSerializationAssemblies>On</GenerateSerializationAssemblies>
    <SDK40ToolsPath>C:\Program Files (x86)\Microsoft SDKs\Windows\v8.1A\bin\NETFX 4.5.1 Tools\x64</SDK40ToolsPath>
  </PropertyGroup>