Cannot use PostSharp with .NET 4.6.2

Question

I am using PostSharp and have just upgraded my solution to .NET 4.6.2

After installing the package System.ValueTuple I get a BindingException: Ambiguous assembly binding policies exception in the output when trying to build the main project with PostSharp enabled.

Unhandled exception (4.3.30.0, postsharp-net40-x86-srv.exe, CLR 4.0.30319.394802, Release): PostSharp.Sdk.CodeModel.BindingException: Ambiguous assembly binding policies: Assembly 'system.runtime, version=4.0.0.0, culture=neutral, publickeytoken=b03f5f7f11d50a3a' redirects both to 'system.runtime, version=4.1.1.0, culture=neutral, publickeytoken=b03f5f7f11d50a3a' and 'system.runtime, version=4.0.20.0, culture=neutral, publickeytoken=b03f5f7f11d50a3a'.
   at PostSharp.Sdk.CodeModel.AssemblyBindingPolicyManager.EvaluatePolicy(IAssemblyName assemblyName, Boolean evaluateSystemPolicies)
   at PostSharp.Sdk.CodeModel.CompareExtensions.^4+F3cylo(IAssemblyName _0, IAssemblyName _1, AssemblyBindingPolicyManager _2, BindingOptions _3, Boolean _4)
   at PostSharp.Sdk.CodeModel.ModuleDeclaration.FindAssembly(IAssemblyName assemblyName, BindingOptions bindingOptions)
   at PostSharp.Sdk.CodeModel.ModuleDeclaration.^nQbUijLO(String _0, IAssemblyName _1, BindingOptions _2)
   at PostSharp.Sdk.CodeModel.ModuleDeclaration.FindType(Type reflectionType, BindingOptions bindingOptions)
   at PostSharp.Sdk.CodeModel.DeclarationCache.^pFnf8wEt()
   at PostSharp.Sdk.CodeModel.TypeRefDeclaration.get_TypeIdentifier()
   at PostSharp.Sdk.CodeModel.CompareExtensions.DefinitionMatchesReference(INamedType definition, INamedType reference, BindingOptions options)
   at PostSharp.Sdk.CodeModel.TypeRefDeclaration.^A9yFoe2uB3TC(ITypeSignature _0, BindingOptions _1)
   at PostSharp.Sdk.CodeModel.TypeRefDeclaration.MatchesReference(ITypeSignature reference)
   at PostSharp.Sdk.CodeModel.Collections.CustomAttributeDeclarationCollection.Contains(IType type)
   at PostSharp.Sdk.Extensibility.Tasks.MulticastAttributeTask.^SgrhoGlQ(AssemblyRefDeclaration _0)
   at PostSharp.Sdk.Extensibility.Tasks.MulticastAttributeTask.^+GwnKh4ZYHu3()
   at PostSharp.Sdk.Extensibility.Tasks.MulticastAttributeTask.Execute()
   at PostSharp.Sdk.Extensibility.Project.ExecutePhase(String phase)
   at PostSharp.Sdk.Extensibility.Project.Execute()
   at PostSharp.Hosting.PostSharpObject.ExecuteProjects()
   at PostSharp.Hosting.PostSharpObject.InvokeProject(ProjectInvocation projectInvocation).

Here is the relevant binding redirect in my Web.config

  <dependentAssembly>
    <assemblyIdentity name="System.Runtime" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.1.1.0" newVersion="4.1.1.0" />
  </dependentAssembly>

Answer 1

This can be fixed by upgrading to the PostSharp 5.0 preview

https://www.nuget.org/packages/PostSharp/5.0.21-preview https://www.postsharp.net/downloads/postsharp-5.0