I've upgraded a solution to use MSBuild 4.0. It compiles but I get lots of warnings, for example:
"T:\projects\Castle.Core\buildscripts\Build.proj" (Package target) (1) -> "T:\projects\Castle.Core\Castle.Core-vs2008.sln" (Build target) (2:2) -> "T:\projects\Castle.Core\src\Castle.DynamicProxy.Tests\Castle.DynamicProxy.Tests-vs2008.csproj" (default target) (3:2) -> D:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(847,9): warning MSB3644: The reference assemblies for framework ".NETFramework,Version=v4.0.30319" were not found. To resolve this, install the SDK or Targeting Pack for this framework version or retarget your application to a version of the framework for which you have the SDK or Targeting Pack installed. Note that assemblies will be resolved from the Global Assembly Cache (GAC) and will be used in place of reference assemblies. Therefore your assembly may not be correctly targeted for the framework you intend. [T:\projects\Castle.Core\src\Castle.DynamicProxy.Tests\Castle.DynamicProxy.Tests-vs2008.csproj]
How can I fix these warnings? It is related to .NET 4.0 Multitargeting pack or SDK, but there's no SDK for .NET 4.0 AFAIK and Multi-Target pack can not be installed separatly.
Any ideas would be appreciated.