Can't Build aspnetcore app in VS 2017 RC - asp.net-core

Question

After installing the new VS 2017 RC I'm having issues with building my asnetcore app, here is the error that I am receiving:
MSB4131 The "FilesWritten" parameter is not supported by the
"GenerateRuntimeConfigurationFiles" task. Verify the parameter exists
on the task, and it is a gettable public instance property.
Here is my .csproj file:
<Project ToolsVersion="15.0" Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net462</TargetFramework>
<PreserveCompilationContext>true</PreserveCompilationContext>
</PropertyGroup>
<PropertyGroup Condition="'$(TargetFramework)' == 'net462'">
<RuntimeIdentifier>win7-x64</RuntimeIdentifier>
</PropertyGroup>
<PropertyGroup>
<PackageTargetFallback>$(PackageTargetFallback);portable-net45+win8+wp8+wpa81;</PackageTargetFallback>
</PropertyGroup>
<PropertyGroup>
<UserSecretsId>aspnet-HobbyQuarters.Web-e309acfb-31ce-4333-a350-edb5d1c073d3</UserSecretsId>
</PropertyGroup>
<ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp1.0'">
<PackageReference Include="Microsoft.NETCore.App">
<Version>1.0.1</Version>
</PackageReference>
<PackageReference Include="System.ComponentModel.Annotations" Version="4.3.0" />
</ItemGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Diagnostics" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.Mvc" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.Routing" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.Server.IISIntegration" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Logging" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.Owin" Version="1.1.0" />
<PackageReference Include="Microsoft.VisualStudio.Web.BrowserLink.Loader" Version="14.1.0" />
<PackageReference Include="Nancy">
<Version>2.0.0-barneyrubble</Version>
</PackageReference>
</ItemGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Authentication.Cookies" Version="1.1.0" />
<PackageReference Include="Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore" Version="1.1.0" />
<PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="1.1.0" />
<PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="1.0.0-msbuild2-final" />
</ItemGroup>
<ItemGroup>
<Reference Include="System" />
<Reference Include="System.Data" />
<Reference Include="System.Xml" />
<Reference Include="System.Xml.Linq" />
<Reference Include="Microsoft.CSharp" />
<Reference Include="System.ComponentModel.DataAnnotations" />
</ItemGroup>
<ItemGroup>
<DotNetCliToolReference Include="Microsoft.Extensions.SecretManager.Tools" Version="1.0.0-msbuild2-final" />
<DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="1.0.0-msbuild2-final" />
</ItemGroup>
<ItemGroup>
<Folder Include="Tasks\" />
</ItemGroup>
</Project>

Answer 1

Launch Task Manager
end all existing MSBuild tasks.
Rebuild your project(s). it should work just fine.
Beside. your .csproj looks just fine to me; however, it looks like its setup to run in two different environment perhaps console and aspcore 1.0

Answer 2

So it looks like this was related to having multiple projects with different msbuild tools versions.
I had older projects that weren't using the new convention of referencing the tools: ToolsVersion="15.0" Sdk="Microsoft.NET.Sdk.Web"...
Once I changed them to use this convention everything started to work.