ASP.NET Compiler complaining of mismatching framework versions with MiniProfiler

I have an MVC3 project that I upgraded from VS2010 to VS2012. The project also has a reference to MiniProfiler. Our application compiles and runs fine in VS2012 without any warnings/errors. Both assemblies load fine when running with IIS Express. When using the ASP.NET Compiler tool, however, I get the following warning:

Microsoft (R) ASP.NET Compilation Tool version 4.0.30319.17929 Utility
to precompile an ASP.NET application Copyright (C) Microsoft
Corporation. All rights reserved.

(0): warning : The following assembly has dependencies on a version of
the .NET Framework that is higher than the target and might not load
correctly during runtime causing a failure: MiniProfiler,
Version=2.1.0.0, Culture=neutral, PublicKeyToken=b44f9351044011a3. The
dependencies are: System.Data.Linq, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089. You should either ensure that the
dependent assembly is correct for the target framework, or ensure that
the target framework you are addressing is that of the dependent
assembly.

We don’t have an explicit reference to System.Data.Linq. Up until the update to VS2012, we didn’t have any errors. The MiniProfiler version is indeed targeting .NET 4.0 (as is our application). What could be causing this warning?

Answers:

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Method 1

I was finally able to fix it with a tip from this answer. I added the following <add> line in the web.config:

<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <!-- etc... -->
        <add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
        <!-- etc... -->
      </assemblies>
    </compilation>
  <system.web>
</configuration>

Method 2

Did you changed targetFramework inside Web.confing?

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