Resolving MSB3247 - Found conflicts between different versions of the same dependent assembly

Question

A .NET 3.5 solution ended up with this warning when compiling with msbuild.

Sometimes NDepend might help out but in this case it didn't give any further details. Like Bob I ended up having to resort to opening each assembly in ILDASM until I found the one that was referencing an older version of the dependant assembly.

I did try using MSBUILD from VS 2010 Beta 2 (as the Connect article indicated this was fixed in the next version of the CLR) but that didn't provide any more detail either (maybe fixed post Beta 2)

Is there a better (more automated) approach?

Answer 1

Change the "MSBuild project build output verbosity" to "Detailed" or above. To do this, follow these steps:

1. Bring up the Options dialog (Tools -> Options...).
2. In the left-hand tree, select the Projects and Solutions node, and then select Build and Run.
   • Note: if this node doesn't show up, make sure that the checkbox at the bottom of the dialog Show all settings is checked.

3. In the tools/options page that appears, set the MSBuild project build output verbosity level to the appropriate setting depending on your version:

   • Diagnostics when on VS2012, VS2013 or VS2015 (the message in these versions says you should use "Detailed", but this is plain wrong, you should use "Diagnostics")
   • Detailed when you're on VS2010
   • Normal will suffice in VS2008 or older.
4. Build the project and look in the output window.

Check out the MSBuild messages. The ResolveAssemblyReferences task, which is the task from which MSB3247 originates, should help you debug this particular issue.

My specific case was an incorrect reference to SqlServerCe. See below. I had two projects referencing two different versions of SqlServerCe. I went to the project with the older version, removed the reference, then added the correct reference.

Target ResolveAssemblyReferences:
    Consider app.config remapping of assembly "System.Data.SqlServerCe, ..." 
        from Version "3.5.1.0" [H:\...\Debug\System.Data.SqlServerCe.dll] 
        to Version "9.0.242.0" [C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\PublicAssemblies\System.Data.SqlServerCe.dll]
        to solve conflict and get rid of warning.
    C:\WINDOWS\Microsoft.NET\Framework\v3.5\Microsoft.Common.targets : 
        warning MSB3247: Found conflicts between different versions of the same dependent assembly.

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You do not have to open each assembly to determine the versions of referenced assemblies.

• You can check the Properties of each Reference.
• Open the project properties and check the versions of the References section.
• Open the projects with a Text Editor.
• Use .Net Reflector.