MSB3247: Found conflicts between different versions of the same dependent assembly.

Had been getting this recently in our builds, and have finally tracked it down to conflicting versions of the Microsoft.ReportViewer.Common.dll in our project references. This came about as one of our developers was using VS 2010, but the rest were still back on VS 2008.

Anyway, I thought I’d blog around how we traced this issue down in the end, as it has been perplexing us for quite some time now.

Step 1: Determine which project is causing the reference conflicts
Check your standard build output and make a note of the project file that was in the process of being built when the ResolveAssemblyReferences target failed.

Step 2: Turn on Detailed msbuild output for your build.
You can do this from within Visual Studio, under Tools, Options, Project and Solutions, Build and Run, MSBuild verbosity = Detailed

Step 3: Determine which reference is at fault
Do a build of the project file(s) that is/are causing these reference failures, and note the lines in the diagnostic build output, where you will see assembly references attempting to be resolved, but unable to find matching references. This should put you on the right track for resolving what has gone wrong with your solution.