Could not load file or assembly 'Microsoft.Practices.Unity - asp.net-mvc-3

Question

I tried install unity.mvc4 using NuGet while installing it gave an error because it required .net4.5 framework so I uninstalled it and remove the package file and installed unity.MVC3.
Now I tried to run the application and it gives me the error below.
I checked the web.config and no entry in web.config. I don't know from where it is referring the version=3.0.0. Please help me to resolve the issue. I don't want unity 3.0 version I want unity 2.1.
Server Error in '/' Application.
Could not load file or assembly 'Microsoft.Practices.Unity,
Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or
one of its dependencies. The system cannot find the file specified.
Description: An unhandled exception occurred during the execution of
the current web request. Please review the stack trace for more
information about the error and where it originated in the code.
Exception Details: System.IO.FileNotFoundException: Could not load
file or assembly 'Microsoft.Practices.Unity, Version=3.0.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its
dependencies. The system cannot find the file specified.
Source Error:
An unhandled exception was generated during the execution of the
current web request. Information regarding the origin and location of
the exception can be identified using the exception stack trace below.
Assembly Load Trace: The following information can be helpful to
determine why the assembly 'Microsoft.Practices.Unity,
Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'
could not be loaded.
=== Pre-bind state information === LOG: User = xxxxx LOG: DisplayName = Microsoft.Practices.Unity,
Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
(Fully-specified) LOG: Appbase =
Stack Trace:
[FileNotFoundException: Could not load file or assembly
'Microsoft.Practices.Unity, Version=3.0.0.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The
system cannot find the file specified.]
Unity.Mvc4.UnityDependencyResolver.DisposeOfChildContainer() +0
Unity.Mvc4.RequestLifetimeHttpModule.b__0(Object sender,
EventArgs e) +31
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
+136 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69
Version Information: Microsoft .NET Framework Version:4.0.30319;
ASP.NET Version:4.0.30319.17929

Answer 1

Within your web.config, add the following in the runtime section:
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="Microsoft.Practices.Unity" publicKeyToken="31bf3856ad364e35" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-3.5.0.0" newVersion="3.5.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Microsoft.Practices.ServiceLocation" publicKeyToken="31bf3856ad364e35" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-1.3.0.0" newVersion="1.3.0.0" />
</dependentAssembly>
</assemblyBinding>