diff --git a/build/common.project.props b/build/common.project.props
index e2e3c0c11dc..79a9353911f 100644
--- a/build/common.project.props
+++ b/build/common.project.props
@@ -10,20 +10,24 @@
 
   <!-- Common -->
   <PropertyGroup>
+    <IsBuildOnlyXPLATProjects>$(DotNetBuildFromSource)</IsBuildOnlyXPLATProjects>
     <RestoreProjectStyle>PackageReference</RestoreProjectStyle>
     <NETFXTargetFrameworkVersion>v4.7.2</NETFXTargetFrameworkVersion>
     <NETFXTargetFramework>net472</NETFXTargetFramework>
     <NETCoreTargetFramework>netcoreapp2.1</NETCoreTargetFramework>
+    <NETCoreTargetFramework Condition="'$(DotNetBuildFromSource)' == 'true'">net6.0</NETCoreTargetFramework>
     <NETCoreTestTargetFramework>netcoreapp5.0</NETCoreTestTargetFramework>
-    <IsBuildOnlyXPLATProjects>$(DotNetBuildFromSource)</IsBuildOnlyXPLATProjects>
     <NetStandardVersion>netstandard2.0</NetStandardVersion>
+    <NetStandardVersion Condition="'$(DotNetBuildFromSource)' == 'true'">net6.0</NetStandardVersion>
     <TargetFrameworksExe>$(NETFXTargetFramework);$(NETCoreTargetFramework)</TargetFrameworksExe>
     <TargetFrameworksExe Condition="'$(IsBuildOnlyXPLATProjects)' == 'true' OR '$(IsXPlat)' == 'true'">$(NETCoreTargetFramework)</TargetFrameworksExe>
     <TargetFrameworksExeForSigning>$(TargetFrameworksExe);netcoreapp5.0</TargetFrameworksExeForSigning>
     <TargetFrameworksExeForSigning Condition=" '$(IsXPlat)' == 'true' ">$(NETCoreTargetFramework);netcoreapp5.0</TargetFrameworksExeForSigning>
+    <TargetFrameworksExeForSigning Condition="'$(DotNetBuildFromSource)' == 'true'">$(TargetFrameworksExe);net6.0</TargetFrameworksExeForSigning>
     <TargetFrameworksLibrary>$(NETFXTargetFramework);$(NetStandardVersion)</TargetFrameworksLibrary>
     <TargetFrameworksLibrary Condition="'$(IsBuildOnlyXPLATProjects)' == 'true'">$(NetStandardVersion)</TargetFrameworksLibrary>
     <TargetFrameworksLibraryForSigning>$(TargetFrameworksLibrary);netcoreapp5.0</TargetFrameworksLibraryForSigning>
+    <TargetFrameworksLibraryForSigning Condition="'$(DotNetBuildFromSource)' == 'true'">$(TargetFrameworksLibrary);net6.0</TargetFrameworksLibraryForSigning>
     <TargetFrameworksLibraryForCrossVerificationTests>$(NETFXTargetFramework);netcoreapp5.0</TargetFrameworksLibraryForCrossVerificationTests>
     <RepositoryRootDirectory>$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), 'README.md'))\</RepositoryRootDirectory>
     <BuildCommonDirectory>$(RepositoryRootDirectory)build\</BuildCommonDirectory>
@@ -52,6 +56,8 @@
     <MicrosoftDotNetBuildTasksFeedFilePath>$(SolutionPackagesFolder)microsoft.dotnet.build.tasks.feed\6.0.0-beta.20528.5\tools\netcoreapp2.1\Microsoft.DotNet.Build.Tasks.Feed.dll</MicrosoftDotNetBuildTasksFeedFilePath>
     <MicrosoftDotNetMaestroTasksFilePath>$(SolutionPackagesFolder)microsoft.dotnet.maestro.tasks\1.1.0-beta.21378.2\tools\netcoreapp3.1\Microsoft.DotNet.Maestro.Tasks.dll</MicrosoftDotNetMaestroTasksFilePath>
     <NoWarn>$(NoWarn);NU5105;MSB3277</NoWarn>
+    <!-- additional warnings new in .NET 6 that we need to disable when building with source-build -->
+    <NoWarn Condition="'$(DotNetBuildFromSource)' == 'true'">$(NoWarn);CS1998;CA1416;CS0618;CS1574</NoWarn>
   </PropertyGroup>
 
   <!-- Defaults -->
@@ -85,6 +91,7 @@
     <!-- Same as SDK default, but without CandidateAssemblyFiles in front, which would search in Content items -->
     <AssemblySearchPaths>{HintPathFromItem};{TargetFrameworkDirectory};{RawFileName}</AssemblySearchPaths>
     <LangVersion>9</LangVersion>
+    <LangVersion Condition="'$(DotNetBuildFromSource)' == 'true'">latest</LangVersion>
   </PropertyGroup>
 
   <!-- DEBUG specific configuration settings -->
diff --git a/build/common.targets b/build/common.targets
index 7a353ebf8e3..67f0f0426e7 100644
--- a/build/common.targets
+++ b/build/common.targets
@@ -6,7 +6,7 @@
     <IsDesktop>true</IsDesktop>
   </PropertyGroup>
 
-  <PropertyGroup Condition=" $(TargetFramework.StartsWith('netcoreapp')) OR $(TargetFramework.StartsWith('netstandard')) ">
+  <PropertyGroup Condition=" $(TargetFramework.StartsWith('netcoreapp')) OR $(TargetFramework.StartsWith('netstandard')) OR $(TargetFramework.StartsWith('net6')) ">
     <DefineConstants>$(DefineConstants);IS_CORECLR</DefineConstants>
     <IsCore>true</IsCore>
   </PropertyGroup>
@@ -65,6 +65,11 @@
     <None Include="$(MSBuildThisFileDirectory)..\icon.png" Pack="true" PackagePath="\" Visible="false" />
   </ItemGroup>
 
+    <!-- Don't use PublicApiAnalyzer on source-build .NET -->
+  <PropertyGroup Condition=" '$(DotNetBuildFromSource)' == 'true' ">
+    <UsePublicApiAnalyzer>false</UsePublicApiAnalyzer>
+  </PropertyGroup>
+
   <!-- Projects we pack become public APIs that others can use -->
   <PropertyGroup Condition=" '$(IsBuildOnlyXPLATProjects)' != 'true' and '$(PackProject)' == 'true' ">
     <UsePublicApiAnalyzer Condition=" '$(UsePublicApiAnalyzer)' == '' " >true</UsePublicApiAnalyzer>
diff --git a/build/packages.targets b/build/packages.targets
index 614a0ca6837..c11557248ee 100644
--- a/build/packages.targets
+++ b/build/packages.targets
@@ -2,6 +2,8 @@
     <PropertyGroup>
         <MicrosoftBuildPackageVersion Condition="'$(MicrosoftBuildPackageVersion)' == ''">16.8.0</MicrosoftBuildPackageVersion>
         <NewtonsoftJsonPackageVersion Condition="$(NewtonsoftJsonPackageVersion) == ''">13.0.1</NewtonsoftJsonPackageVersion>
+        <MicrosoftWebXdtPackageVersion Condition="'$(MicrosoftWebXdtPackageVersion)' == ''">3.0.0</MicrosoftWebXdtPackageVersion>
+        <SystemComponentModelCompositionPackageVersion Condition="'$(SystemComponentModelCompositionPackageVersion)' == ''">4.5.0</SystemComponentModelCompositionPackageVersion>
         <SystemPackagesVersion>4.3.0</SystemPackagesVersion>
         <VSFrameworkVersion>17.0.0-previews-1-31321-016</VSFrameworkVersion>
         <VSServicesVersion>16.153.0</VSServicesVersion>
@@ -42,10 +44,10 @@
         <PackageReference Update="Microsoft.VisualStudio.VCProjectEngine" Version="$(VSFrameworkVersion)" />
         <PackageReference Update="Microsoft.VisualStudio.Workspace.VSIntegration" Version="17.0.7-preview-0001-g5492e466a9" />
         <PackageReference Update="Microsoft.VSSDK.BuildTools" Version="17.0.1600" />
-        <PackageReference Update="Microsoft.Web.Xdt" Version="3.0.0" />
+        <PackageReference Update="Microsoft.Web.Xdt" Version="$(MicrosoftWebXdtPackageVersion)" />
         <PackageReference Update="Newtonsoft.Json" Version="$(NewtonsoftJsonPackageVersion)" />
         <PackageReference Update="SharpZipLib" Version="1.3.2" />
-        <PackageReference Update="System.ComponentModel.Composition" Version="4.5.0" />
+        <PackageReference Update="System.ComponentModel.Composition" Version="$(SystemComponentModelCompositionPackageVersion)" />
         <!--
           The Microsoft.VisualStudio.SDK metapackage brings in System.Threading.Tasks.Dataflow 4.11.1 (assembly version 4.9.5.0).
           However, our MSBuild integration tests use Microsoft.Build 16.8.0, which requires System.Threading.Tasks.Dataflow 4.9.0 (assembly version 4.9.3.0).
diff --git a/eng/source-build/build.sh b/eng/source-build/build.sh
index 3bb69b2b00c..70bb7220585 100755
--- a/eng/source-build/build.sh
+++ b/eng/source-build/build.sh
@@ -13,6 +13,25 @@ while [[ -h $source ]]; do
   [[ $source != /* ]] && source="$scriptroot/$source"
 done
 
+
+while [[ $# > 0 ]]; do
+    lowerI="$(echo $1 | awk '{print tolower($0)}')"
+    case $lowerI in
+        --configuration|-c)
+            configuration=$2
+            shift
+            ;;
+        -*)
+            # just eat this so we don't try to pass it along to MSBuild
+            export DOTNET_CORESDK_NOPRETTYPRINT=1
+            ;;
+        *)
+            args="$args $1"
+            ;;
+    esac
+    shift
+done
+
 function ReadGlobalVersion {
   local key=$1
   local global_json_file="$scriptroot/global.json"
@@ -40,8 +59,25 @@ function GetNuGetPackageCachePath {
   fi
 }
 
-export DOTNET=${DOTNET:-dotnet}
+if [[ "$DOTNET" == "" && "$DOTNET_PATH" != "" ]]; then
+  export DOTNET="$DOTNET_PATH/dotnet"
+else
+  ReadGlobalVersion dotnet
+  export SDK_VERSION=$_ReadGlobalVersion
+
+  mkdir -p "$scriptroot/../../cli"
+  curl -o "$scriptroot/../../cli/dotnet-install.sh" -L https://dot.net/v1/dotnet-install.sh
+
+  if (( $? )); then
+    echo "Could not download 'dotnet-install.sh' script. Please check your network and try again!"
+    exit 1
+  fi
+  chmod +x "$scriptroot/../../cli/dotnet-install.sh"
+
+  "$scriptroot/../../cli/dotnet-install.sh" -v $SDK_VERSION -i "$scriptroot/../../cli"
+  export DOTNET=${DOTNET:-$scriptroot/../../cli/dotnet}
+fi
 
 ReadGlobalVersion Microsoft.DotNet.Arcade.Sdk
 export ARCADE_VERSION=$_ReadGlobalVersion
-"$DOTNET" msbuild "$scriptroot/source-build.proj" /p:DotNetBuildFromSource=true /p:ArcadeBuildFromSource=true "/p:RepoRoot=$scriptroot/../../" "/bl:$scriptroot/../../artifacts/source-build/self/log/source-build.binlog"
+"$DOTNET" msbuild "$scriptroot/source-build.proj" /p:Configuration=$configuration /p:DotNetBuildFromSource=true /p:ArcadeBuildFromSource=true "/p:RepoRoot=$scriptroot/../../" "/bl:$scriptroot/../../artifacts/source-build/self/log/source-build.binlog" $args
diff --git a/eng/source-build/global.json b/eng/source-build/global.json
index 2217a9433a5..2b9604572ad 100644
--- a/eng/source-build/global.json
+++ b/eng/source-build/global.json
@@ -1,4 +1,7 @@
 {
+  "tools": {
+    "dotnet": "6.0.100-preview.7.21379.14"
+  },
   "msbuild-sdks": {
     "Microsoft.DotNet.Arcade.Sdk": "6.0.0-beta.21309.7"
   }
diff --git a/eng/source-build/source-build.proj b/eng/source-build/source-build.proj
index 72058ac888f..cbdd6d819fd 100644
--- a/eng/source-build/source-build.proj
+++ b/eng/source-build/source-build.proj
@@ -4,6 +4,8 @@
 
   <PropertyGroup>
     <ProjectRoot>$(MSBuildThisFileDirectory)../../</ProjectRoot>
+    <ArcadeDir Condition="'$(SOURCE_BUILT_SDK_DIR_ARCADE)' != ''">$(SOURCE_BUILT_SDK_DIR_ARCADE)/tools/</ArcadeDir>
+    <ArcadeDir Condition="'$(ArcadeDir)' == ''">$(NuGetPackageRoot)/microsoft.dotnet.arcade.sdk/$(ARCADE_VERSION)/tools/</ArcadeDir>
   </PropertyGroup>
 
   <Target Name="Build" DependsOnTargets="SourceBuildPostBuild">
@@ -18,14 +20,14 @@
   <Target Name="SourceBuildPostBuild" DependsOnTargets="SourceBuildInnerBuild">
     <Message Text="Running source-build PostBuild target" Importance="High" />
 
-    <MSbuild Projects="$(NuGetPackageRoot)/microsoft.dotnet.arcade.sdk/$(ARCADE_VERSION)/tools/Build.proj"
+    <MSbuild Projects="$(ArcadeDir)/Build.proj"
              Properties="_NETCORE_ENGINEERING_TELEMETRY=AfterSourceBuild;ArcadeBuildFromSource=true;Restore=true;Build=false;Pack=false;Publish=false;Rebuild=false;Test=false;IntegrationTest=false;PerformanceTest=false;PreventPrebuiltBuild=false;BaseInnerSourceBuildCommand=echo skipping internal build with args: "
              Targets="Execute"
             />
 
     <Message Text="Finished restoring Arcade" Importance="High" />
 
-    <MSbuild Projects="$(NuGetPackageRoot)/microsoft.dotnet.arcade.sdk/$(ARCADE_VERSION)/tools/SourceBuild/AfterSourceBuild.proj"
+    <MSbuild Projects="$(ArcadeDir)/SourceBuild/AfterSourceBuild.proj"
              Properties="_NETCORE_ENGINEERING_TELEMETRY=AfterSourceBuild;ArcadeBuildFromSource=true;CurrentRepoSourceBuildArtifactsPackagesDir=$(ProjectRoot)artifacts/nupkgs/"
             />
 
diff --git a/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetPackOutputItemsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetPackOutputItemsTask.cs
index e804dae2f72..2e41c94313c 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetPackOutputItemsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetPackOutputItemsTask.cs
@@ -13,7 +13,7 @@
 
 namespace NuGet.Build.Tasks.Pack
 {
-    public class GetPackOutputItemsTask : Task
+    public class GetPackOutputItemsTask : Microsoft.Build.Utilities.Task
     {
         [Required]
         public string PackageId { get; set; }
diff --git a/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetProjectReferencesFromAssetsFileTask.cs b/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetProjectReferencesFromAssetsFileTask.cs
index 2b5018d0dec..80ad89f961c 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetProjectReferencesFromAssetsFileTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks.Pack/GetProjectReferencesFromAssetsFileTask.cs
@@ -19,7 +19,7 @@ namespace NuGet.Build.Tasks.Pack
     /// This list is then later traversed to determine the version
     /// of the project reference during pack.
     /// </summary>
-    public class GetProjectReferencesFromAssetsFileTask : Task
+    public class GetProjectReferencesFromAssetsFileTask : Microsoft.Build.Utilities.Task
     {
         public string RestoreOutputAbsolutePath { get; set; }
 
diff --git a/src/NuGet.Core/NuGet.Build.Tasks.Pack/IsPackableFalseWarningTask.cs b/src/NuGet.Core/NuGet.Build.Tasks.Pack/IsPackableFalseWarningTask.cs
index be59646cb6f..96825afc1a8 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks.Pack/IsPackableFalseWarningTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks.Pack/IsPackableFalseWarningTask.cs
@@ -7,7 +7,7 @@
 
 namespace NuGet.Build.Tasks.Pack
 {
-    public class IsPackableFalseWarningTask : Task
+    public class IsPackableFalseWarningTask : Microsoft.Build.Utilities.Task
     {
         public ILogger Logger => new MSBuildLogger(Log);
         public override bool Execute()
diff --git a/src/NuGet.Core/NuGet.Build.Tasks.Pack/NuGet.Build.Tasks.Pack.csproj b/src/NuGet.Core/NuGet.Build.Tasks.Pack/NuGet.Build.Tasks.Pack.csproj
index f11dd752bea..c94acffd885 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks.Pack/NuGet.Build.Tasks.Pack.csproj
+++ b/src/NuGet.Core/NuGet.Build.Tasks.Pack/NuGet.Build.Tasks.Pack.csproj
@@ -180,12 +180,15 @@
       <PackagePathDir Condition="'$(TargetFramework)' == '$(NetStandardVersion)'">CoreCLR/</PackagePathDir>
     </PropertyGroup>
     <ItemGroup>
-      <TfmSpecificPackageFile Include="$(OutputPath)\$(ILMergeSubpath)NuGet.Build.Tasks.Pack.dll">
+      <TfmSpecificPackageFile Include="$(OutputPath)\$(ILMergeSubpath)NuGet.Build.Tasks.Pack.dll" Condition="'$(IsBuildOnlyXPLATProjects)' != 'true'">
         <PackagePath>$(PackagePathDir)</PackagePath>
       </TfmSpecificPackageFile>
       <TfmSpecificPackageFile Include="$(OutputPath)\$(ILMergeSubpath)**\NuGet*.resources.dll">
         <PackagePath>$(PackagePathDir)</PackagePath>
       </TfmSpecificPackageFile>
+      <TfmSpecificPackageFile Include="$(OutputPath)\$(ILMergeSubpath)NuGet*.dll" Condition="'$(IsBuildOnlyXPLATProjects)' == 'true'">
+        <PackagePath>$(PackagePathDir)</PackagePath>
+      </TfmSpecificPackageFile>
     </ItemGroup>    
   </Target>
 
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GenerateRestoreGraphFileTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GenerateRestoreGraphFileTask.cs
index 2a60786a835..1e4615a9600 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GenerateRestoreGraphFileTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GenerateRestoreGraphFileTask.cs
@@ -17,7 +17,7 @@ namespace NuGet.Build.Tasks
     /// <summary>
     /// Represents an MSBuild task that performs a command-line based restore.
     /// </summary>
-    public sealed class GenerateRestoreGraphFileTask : Task, ICancelableTask, IDisposable
+    public sealed class GenerateRestoreGraphFileTask : Microsoft.Build.Utilities.Task, ICancelableTask, IDisposable
     {
         internal readonly CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();
 
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetCentralPackageVersionsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetCentralPackageVersionsTask.cs
index 8598fa13f8b..8b580f60901 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetCentralPackageVersionsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetCentralPackageVersionsTask.cs
@@ -10,7 +10,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetCentralPackageVersionsTask : Task
+    public class GetCentralPackageVersionsTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetProjectTargetFrameworksTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetProjectTargetFrameworksTask.cs
index 37c4518517b..42d873cf020 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetProjectTargetFrameworksTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetProjectTargetFrameworksTask.cs
@@ -12,7 +12,7 @@ namespace NuGet.Build.Tasks
     /// Determine the project's targetframework(s) based
     /// on the available properties.
     /// </summary>
-    public class GetProjectTargetFrameworksTask : Task
+    public class GetProjectTargetFrameworksTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetReferenceNearestTargetFrameworkTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetReferenceNearestTargetFrameworkTask.cs
index c705cd2241e..024435a254f 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetReferenceNearestTargetFrameworkTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetReferenceNearestTargetFrameworkTask.cs
@@ -12,7 +12,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetReferenceNearestTargetFrameworkTask : Task
+    public class GetReferenceNearestTargetFrameworkTask : Microsoft.Build.Utilities.Task
     {
         private const string NEAREST_TARGET_FRAMEWORK = "NearestTargetFramework";
         private const string TARGET_FRAMEWORKS = "TargetFrameworks";
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreDotnetCliToolsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreDotnetCliToolsTask.cs
index 02dbbe9074a..9befcc24c52 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreDotnetCliToolsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreDotnetCliToolsTask.cs
@@ -14,7 +14,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetRestoreDotnetCliToolsTask : Task
+    public class GetRestoreDotnetCliToolsTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreFrameworkReferencesTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreFrameworkReferencesTask.cs
index 5b40832590f..afa694b4c7b 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreFrameworkReferencesTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreFrameworkReferencesTask.cs
@@ -10,7 +10,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetRestoreFrameworkReferencesTask : Task
+    public class GetRestoreFrameworkReferencesTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageDownloadsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageDownloadsTask.cs
index 4c8f5464ac6..1cdc06087da 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageDownloadsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageDownloadsTask.cs
@@ -10,7 +10,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetRestorePackageDownloadsTask : Task
+    public class GetRestorePackageDownloadsTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageReferencesTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageReferencesTask.cs
index 71f523007b8..38d8f3ee720 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageReferencesTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestorePackageReferencesTask.cs
@@ -10,7 +10,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetRestorePackageReferencesTask : Task
+    public class GetRestorePackageReferencesTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectJsonPathTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectJsonPathTask.cs
index 6e20d808623..73461471970 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectJsonPathTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectJsonPathTask.cs
@@ -9,7 +9,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetRestoreProjectJsonPathTask : Task
+    public class GetRestoreProjectJsonPathTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectReferencesTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectReferencesTask.cs
index fa7da8c9898..8eaf85ffbec 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectReferencesTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreProjectReferencesTask.cs
@@ -11,7 +11,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class GetRestoreProjectReferencesTask : Task
+    public class GetRestoreProjectReferencesTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// Full path to the msbuild project.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSettingsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSettingsTask.cs
index 43d5904686d..eafc9388f42 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSettingsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSettingsTask.cs
@@ -17,7 +17,7 @@ namespace NuGet.Build.Tasks
     /// <summary>
     /// Get all the settings to be used for project restore.
     /// </summary>
-    public class GetRestoreSettingsTask : Task
+    public class GetRestoreSettingsTask : Microsoft.Build.Utilities.Task
     {
         [Required]
         public string ProjectUniqueName { get; set; }
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSolutionProjectsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSolutionProjectsTask.cs
index 55f3f7bceed..49ebb534df4 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSolutionProjectsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/GetRestoreSolutionProjectsTask.cs
@@ -13,7 +13,7 @@ namespace NuGet.Build.Tasks
     /// <summary>
     /// Convert .metaproj paths to project paths.
     /// </summary>
-    public class GetRestoreSolutionProjectsTask : Task
+    public class GetRestoreSolutionProjectsTask : Microsoft.Build.Utilities.Task
     {
         private const string MetaProjExtension = ".metaproj";
 
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/RestoreTaskEx.cs b/src/NuGet.Core/NuGet.Build.Tasks/RestoreTaskEx.cs
index 4109ae449df..8bd0e5fa0c5 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/RestoreTaskEx.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/RestoreTaskEx.cs
@@ -17,7 +17,7 @@ namespace NuGet.Build.Tasks
     /// <summary>
     /// Represents an MSBuild task that performs a command-line based restore.
     /// </summary>
-    public sealed class RestoreTaskEx : Task, ICancelableTask, IDisposable
+    public sealed class RestoreTaskEx : Microsoft.Build.Utilities.Task, ICancelableTask, IDisposable
     {
         internal readonly CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();
 
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/WarnForInvalidProjectsTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/WarnForInvalidProjectsTask.cs
index 27f077b0c1e..80d8f882230 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/WarnForInvalidProjectsTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/WarnForInvalidProjectsTask.cs
@@ -10,7 +10,7 @@
 
 namespace NuGet.Build.Tasks
 {
-    public class WarnForInvalidProjectsTask : Task
+    public class WarnForInvalidProjectsTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// All known projects.
diff --git a/src/NuGet.Core/NuGet.Build.Tasks/WriteRestoreGraphTask.cs b/src/NuGet.Core/NuGet.Build.Tasks/WriteRestoreGraphTask.cs
index f8d574e3c73..de6b3d499eb 100644
--- a/src/NuGet.Core/NuGet.Build.Tasks/WriteRestoreGraphTask.cs
+++ b/src/NuGet.Core/NuGet.Build.Tasks/WriteRestoreGraphTask.cs
@@ -15,7 +15,7 @@ namespace NuGet.Build.Tasks
     /// <summary>
     /// Generate dg file output.
     /// </summary>
-    public class WriteRestoreGraphTask : Task
+    public class WriteRestoreGraphTask : Microsoft.Build.Utilities.Task
     {
         /// <summary>
         /// DG file entries
diff --git a/src/NuGet.Core/NuGet.Frameworks/NuGet.Frameworks.csproj b/src/NuGet.Core/NuGet.Frameworks/NuGet.Frameworks.csproj
index 65f261dc141..b78b1f2ea28 100644
--- a/src/NuGet.Core/NuGet.Frameworks/NuGet.Frameworks.csproj
+++ b/src/NuGet.Core/NuGet.Frameworks/NuGet.Frameworks.csproj
@@ -4,8 +4,8 @@
 
   <PropertyGroup>
     <Description>NuGet's understanding of target frameworks.</Description>
-    <TargetFrameworks>$(TargetFrameworksLibrary)</TargetFrameworks>
-    <TargetFrameworks Condition="'$(IsBuildOnlyXPLATProjects)' != 'true'">$(TargetFrameworks);net40</TargetFrameworks>
+    <TargetFrameworks Condition="'$(IsBuildOnlyXPLATProjects)' == 'true'">$(TargetFrameworksLibrary);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(IsBuildOnlyXPLATProjects)' != 'true'">$(TargetFrameworksLibrary);net40</TargetFrameworks>
     <TargetFramework />
     <NoWarn>$(NoWarn);CS1591;CS1574;CS1573</NoWarn>
     <PackProject>true</PackProject>
diff --git a/src/NuGet.Core/NuGet.PackageManagement/Context/IDEExecutionContext.cs b/src/NuGet.Core/NuGet.PackageManagement/Context/IDEExecutionContext.cs
index 0bacde25e87..560280d31e0 100644
--- a/src/NuGet.Core/NuGet.PackageManagement/Context/IDEExecutionContext.cs
+++ b/src/NuGet.Core/NuGet.PackageManagement/Context/IDEExecutionContext.cs
@@ -8,7 +8,7 @@
 
 namespace NuGet.PackageManagement
 {
-    public class IDEExecutionContext : ExecutionContext
+    public class IDEExecutionContext : NuGet.ProjectManagement.ExecutionContext
     {
         public ICommonOperations CommonOperations { get; }
 
diff --git a/test/NuGet.Core.Tests/NuGet.Packaging.Test/NuGet.Packaging.Test.csproj b/test/NuGet.Core.Tests/NuGet.Packaging.Test/NuGet.Packaging.Test.csproj
index 75504cb7165..d59cac2caec 100644
--- a/test/NuGet.Core.Tests/NuGet.Packaging.Test/NuGet.Packaging.Test.csproj
+++ b/test/NuGet.Core.Tests/NuGet.Packaging.Test/NuGet.Packaging.Test.csproj
@@ -6,6 +6,8 @@
     <TargetFrameworks>$(TargetFrameworksExeForSigning)</TargetFrameworks>
     <UseParallelXunit>true</UseParallelXunit>
     <Description>Unit tests for NuGet.Packaging.</Description>
+    <!-- remove warnings for obsolete types and methods: SYSLIB0023: RNGCryptoServiceProvider, SYSLIB0026: X509Certificate2() blank constructor -->
+    <NoWarn>SYSLIB0023;SYSLIB0026</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/TestUtilities/Test.Utility/ProjectManagement/TestNuGetProjectContext.cs b/test/TestUtilities/Test.Utility/ProjectManagement/TestNuGetProjectContext.cs
index 6a08e7989f6..a22691026eb 100644
--- a/test/TestUtilities/Test.Utility/ProjectManagement/TestNuGetProjectContext.cs
+++ b/test/TestUtilities/Test.Utility/ProjectManagement/TestNuGetProjectContext.cs
@@ -63,7 +63,7 @@ public FileConflictAction ResolveFileConflict(string message)
 
         public ISourceControlManagerProvider SourceControlManagerProvider { get; set; }
 
-        public ExecutionContext ExecutionContext
+        public NuGet.ProjectManagement.ExecutionContext ExecutionContext
         {
             get { return TestExecutionContext; }
         }
@@ -101,7 +101,7 @@ public Guid OperationId
         }
     }
 
-    public class TestExecutionContext : ExecutionContext
+    public class TestExecutionContext : NuGet.ProjectManagement.ExecutionContext
     {
         public TestExecutionContext(PackageIdentity directInstall)
         {