diff --git a/azure-pipelines-PR.yml b/azure-pipelines-PR.yml
index 827b97f33ac..8647164d91a 100644
--- a/azure-pipelines-PR.yml
+++ b/azure-pipelines-PR.yml
@@ -774,7 +774,7 @@ stages:
               workingDirectory: $(Build.SourcesDirectory)
               installationPath: $(Build.SourcesDirectory)/.dotnet
           - script: .\eng\common\dotnet.cmd
-          - script: .\Build.cmd $(_kind) -pack -c $(_BuildConfig)
+          - script: .\Build.cmd $(_kind) -ci -pack -c $(_BuildConfig)
             env:
               NativeToolsOnMachine: true
             displayName: Initial build and prepare packages.
diff --git a/eng/Version.Details.props b/eng/Version.Details.props
index fb64aafcc65..d39d8b4f083 100644
--- a/eng/Version.Details.props
+++ b/eng/Version.Details.props
@@ -19,19 +19,19 @@ This file should be imported by eng/Versions.props
     <optimizationwindows_ntx64MIBCRuntimePackageVersion>1.0.0-prerelease.26318.1</optimizationwindows_ntx64MIBCRuntimePackageVersion>
     <optimizationwindows_ntx86MIBCRuntimePackageVersion>1.0.0-prerelease.26318.1</optimizationwindows_ntx86MIBCRuntimePackageVersion>
     <!-- dotnet-roslyn dependencies -->
-    <MicrosoftCodeAnalysisPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisPackageVersion>
-    <MicrosoftCodeAnalysisCompilersPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisCompilersPackageVersion>
-    <MicrosoftCodeAnalysisCSharpPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisCSharpPackageVersion>
-    <MicrosoftCodeAnalysisEditorFeaturesPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisEditorFeaturesPackageVersion>
-    <MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion>
-    <MicrosoftCodeAnalysisExternalAccessFSharpPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisExternalAccessFSharpPackageVersion>
-    <MicrosoftCodeAnalysisFeaturesPackageVersion>5.10.0-1.26358.9</MicrosoftCodeAnalysisFeaturesPackageVersion>
-    <MicrosoftVisualStudioLanguageServicesPackageVersion>5.10.0-1.26358.9</MicrosoftVisualStudioLanguageServicesPackageVersion>
+    <MicrosoftCodeAnalysisPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisPackageVersion>
+    <MicrosoftCodeAnalysisCompilersPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisCompilersPackageVersion>
+    <MicrosoftCodeAnalysisCSharpPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisCSharpPackageVersion>
+    <MicrosoftCodeAnalysisEditorFeaturesPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisEditorFeaturesPackageVersion>
+    <MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion>
+    <MicrosoftCodeAnalysisExternalAccessFSharpPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisExternalAccessFSharpPackageVersion>
+    <MicrosoftCodeAnalysisFeaturesPackageVersion>5.10.0-1.26359.5</MicrosoftCodeAnalysisFeaturesPackageVersion>
+    <MicrosoftVisualStudioLanguageServicesPackageVersion>5.10.0-1.26359.5</MicrosoftVisualStudioLanguageServicesPackageVersion>
     <!-- dotnet-runtime dependencies -->
-    <SystemCollectionsImmutablePackageVersion>10.0.2</SystemCollectionsImmutablePackageVersion>
-    <SystemCompositionPackageVersion>10.0.2</SystemCompositionPackageVersion>
-    <SystemDiagnosticsDiagnosticSourcePackageVersion>10.0.2</SystemDiagnosticsDiagnosticSourcePackageVersion>
-    <SystemReflectionMetadataPackageVersion>10.0.2</SystemReflectionMetadataPackageVersion>
+    <SystemCollectionsImmutablePackageVersion>10.0.8</SystemCollectionsImmutablePackageVersion>
+    <SystemCompositionPackageVersion>10.0.8</SystemCompositionPackageVersion>
+    <SystemDiagnosticsDiagnosticSourcePackageVersion>10.0.8</SystemDiagnosticsDiagnosticSourcePackageVersion>
+    <SystemReflectionMetadataPackageVersion>10.0.8</SystemReflectionMetadataPackageVersion>
     <SystemSecurityCryptographyXmlPackageVersion>10.0.8</SystemSecurityCryptographyXmlPackageVersion>
   </PropertyGroup>
   <!--Property group for alternate package version names-->
diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index e446d5e3f40..4147079d860 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -18,58 +18,58 @@
       <Uri>https://github.com/dotnet/msbuild</Uri>
       <Sha>ad7e074ca3a93f4af30405c4cd24db04151d7ce8</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.Features" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis.Features" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.EditorFeatures" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis.EditorFeatures" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.EditorFeatures.Text" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis.EditorFeatures.Text" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.ExternalAccess.FSharp" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis.ExternalAccess.FSharp" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.CSharp" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis.CSharp" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.Compilers" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.CodeAnalysis.Compilers" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.VisualStudio.LanguageServices" Version="5.10.0-1.26358.9">
+    <Dependency Name="Microsoft.VisualStudio.LanguageServices" Version="5.10.0-1.26359.5">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>35967bab3447f7edd6162baee7048f801f18fffe</Sha>
+      <Sha>4d24fd6cc1bd247579fc2cf42442b03004ecc7bd</Sha>
     </Dependency>
     <!-- Necessary for source-build. This allows the live version of the package to be used by source-build. -->
-    <Dependency Name="System.Collections.Immutable" Version="10.0.2">
+    <Dependency Name="System.Collections.Immutable" Version="10.0.8">
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>
       </Sha>
     </Dependency>
     <!-- Necessary for source-build. This allows the live version of the package to be used by source-build. -->
-    <Dependency Name="System.Composition" Version="10.0.2">
+    <Dependency Name="System.Composition" Version="10.0.8">
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>
       </Sha>
     </Dependency>
     <!-- Necessary for source-build. This allows the live version of the package to be used by source-build. -->
-    <Dependency Name="System.Diagnostics.DiagnosticSource" Version="10.0.2">
+    <Dependency Name="System.Diagnostics.DiagnosticSource" Version="10.0.8">
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>
       </Sha>
     </Dependency>
     <!-- Necessary for source-build. This allows the live version of the package to be used by source-build. -->
-    <Dependency Name="System.Reflection.Metadata" Version="10.0.2">
+    <Dependency Name="System.Reflection.Metadata" Version="10.0.8">
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>
       </Sha>
diff --git a/eng/Versions.props b/eng/Versions.props
index 60486fabcaa..8f756067e4d 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -103,16 +103,17 @@
     <MicrosoftVisualStudioShellPackagesVersion>18.0.2188-preview.1</MicrosoftVisualStudioShellPackagesVersion>
     <VisualStudioProjectSystemPackagesVersion>18.0.1237-pre</VisualStudioProjectSystemPackagesVersion>
     <VisualStudioShellProjectsPackages>18.0.2077-preview.1</VisualStudioShellProjectsPackages>
-    <MicrosoftVisualStudioThreadingPackagesVersion>18.0.5</MicrosoftVisualStudioThreadingPackagesVersion>
+    <MicrosoftVisualStudioThreadingPackagesVersion>18.7.19</MicrosoftVisualStudioThreadingPackagesVersion>
   
     <!-- Roslyn packages. Rest is managed by maestro bot and is in the imported .Details.props file -->
     <MicrosoftCodeAnalysisTestResourcesProprietaryVersion>2.0.28</MicrosoftCodeAnalysisTestResourcesProprietaryVersion>
     <!-- Visual Studio Shell packages -->
     <MicrosoftVisualStudioInteropVersion>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftVisualStudioInteropVersion>
     <MicrosoftVisualStudioImagingInterop140DesignTimeVersion>$(VisualStudioShellProjectsPackages)</MicrosoftVisualStudioImagingInterop140DesignTimeVersion>
-    <MicrosoftVisualStudioShellInteropVersion>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftVisualStudioShellInteropVersion>
-    <MicrosoftVisualStudioTextManagerInteropVersion>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftVisualStudioTextManagerInteropVersion>
-    <MicrosoftVisualStudioOLEInteropVersion>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftVisualStudioOLEInteropVersion>
+    <!-- Interop packages are pinned to the version required by Microsoft.VisualStudio.SDK (pulled transitively via Microsoft.CodeAnalysis.ExternalAccess.FSharp), which is newer than the other shell packages. -->
+    <MicrosoftVisualStudioShellInteropVersion>18.9.438</MicrosoftVisualStudioShellInteropVersion>
+    <MicrosoftVisualStudioTextManagerInteropVersion>18.9.438</MicrosoftVisualStudioTextManagerInteropVersion>
+    <MicrosoftVisualStudioOLEInteropVersion>18.9.438</MicrosoftVisualStudioOLEInteropVersion>
     <MicrosoftVisualStudioShellDesignVersion>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftVisualStudioShellDesignVersion>
     <MicrosoftInternalVisualStudioShellFrameworkVersion>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftInternalVisualStudioShellFrameworkVersion>
     <MicrosoftVisualStudioPackageLanguageService150Version>$(MicrosoftVisualStudioShellPackagesVersion)</MicrosoftVisualStudioPackageLanguageService150Version>
@@ -127,7 +128,12 @@
     <MicrosoftVisualStudioEditorVersion>$(VisualStudioEditorPackagesVersion)</MicrosoftVisualStudioEditorVersion>
     <MicrosoftVisualStudioLanguageStandardClassificationVersion>$(VisualStudioEditorPackagesVersion)</MicrosoftVisualStudioLanguageStandardClassificationVersion>
     <MicrosoftVisualStudioLanguageIntellisenseVersion>$(VisualStudioEditorPackagesVersion)</MicrosoftVisualStudioLanguageIntellisenseVersion>
-    <MicrosoftVisualStudioPlatformVSEditorVersion>$(VisualStudioEditorPackagesVersion)</MicrosoftVisualStudioPlatformVSEditorVersion>
+    <!-- Microsoft.VisualStudio.Platform.VSEditor is the runtime implementation of the editor. Unlike the other editor
+         packages it is not pulled transitively by Microsoft.CodeAnalysis.ExternalAccess.FSharp, so it stays at the
+         explicit pin while Microsoft.VisualStudio.Text.* / .Editor get bumped to 18.9.123 transitively. Pin VSEditor to
+         the matching 18.9.123 so its implementation types load against the newer Text.Internal interfaces; otherwise the
+         VsMocks MEF catalog throws ReflectionTypeLoadException and every legacy VS unit test fails. -->
+    <MicrosoftVisualStudioPlatformVSEditorVersion>18.9.123</MicrosoftVisualStudioPlatformVSEditorVersion>
     <MicrosoftVisualStudioTextUIWpfVersion>$(VisualStudioEditorPackagesVersion)</MicrosoftVisualStudioTextUIWpfVersion>
     <NuGetVisualStudioVersion>17.14.0</NuGetVisualStudioVersion>
     <MicrosoftVisualStudioExtensibilityTestingVersion>0.1.800-beta</MicrosoftVisualStudioExtensibilityTestingVersion>
@@ -136,6 +142,20 @@
     <!-- Visual Studio Threading packages -->
     <MicrosoftVisualStudioThreadingVersion>$(MicrosoftVisualStudioThreadingPackagesVersion)</MicrosoftVisualStudioThreadingVersion>
 
+    <!-- Transitive packages pinned to the versions required by Microsoft.CodeAnalysis.ExternalAccess.FSharp
+         (via Microsoft.VisualStudio.SDK 18.9.496), which are newer than the versions the Shell packages pull in.
+         Pinning them avoids MSB3277 assembly version conflicts across the vsintegration projects. -->
+    <MicrosoftVisualStudioValidationVersion>18.7.1</MicrosoftVisualStudioValidationVersion>
+    <MicrosoftVisualStudioRpcContractsVersion>18.9.453</MicrosoftVisualStudioRpcContractsVersion>
+    <MicrosoftServiceHubFrameworkVersion>4.10.128</MicrosoftServiceHubFrameworkVersion>
+    <StreamJsonRpcVersion>2.26.5</StreamJsonRpcVersion>
+
+    <!-- Microsoft.VisualStudio.Shell.15.0 18.9.x references Microsoft.VisualStudio.SolutionPersistence at runtime but
+         does not declare it as a NuGet dependency (it is expected to come from the VS install). The standalone VS unit
+         test host loads Shell.15.0 into a MEF catalog, so the assembly must be deployed next to it or Assembly.GetTypes
+         throws and every legacy VS unit test fails. -->
+    <MicrosoftVisualStudioSolutionPersistenceVersion>1.0.52</MicrosoftVisualStudioSolutionPersistenceVersion>
+
     <!-- Visual Studio Project System packages-->
     <MicrosoftVisualStudioProjectSystemVersion>$(VisualStudioProjectSystemPackagesVersion)</MicrosoftVisualStudioProjectSystemVersion>
     <MicrosoftVisualStudioProjectSystemManagedVersion>2.3.6152103</MicrosoftVisualStudioProjectSystemManagedVersion>
diff --git a/vsintegration/Directory.Build.targets b/vsintegration/Directory.Build.targets
index 6d09285feca..16099d6637c 100644
--- a/vsintegration/Directory.Build.targets
+++ b/vsintegration/Directory.Build.targets
@@ -14,6 +14,11 @@
     <PackageReference Include="System.Composition" Version="$(SystemCompositionVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
+    <!-- Pinned to match Microsoft.CodeAnalysis.ExternalAccess.FSharp's transitive versions and avoid MSB3277 conflicts. -->
+    <PackageReference Include="Microsoft.VisualStudio.Validation" Version="$(MicrosoftVisualStudioValidationVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
+    <PackageReference Include="Microsoft.VisualStudio.RpcContracts" Version="$(MicrosoftVisualStudioRpcContractsVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
+    <PackageReference Include="Microsoft.ServiceHub.Framework" Version="$(MicrosoftServiceHubFrameworkVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
+    <PackageReference Include="StreamJsonRpc" Version="$(StreamJsonRpcVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
   </ItemGroup>
 
   <!-- New VS does not allow embedded interop assemblies ... this turns off the target that turns it on -->
diff --git a/vsintegration/tests/Directory.Build.targets b/vsintegration/tests/Directory.Build.targets
index 14437118703..2bbbb8d4d4c 100644
--- a/vsintegration/tests/Directory.Build.targets
+++ b/vsintegration/tests/Directory.Build.targets
@@ -1,3 +1,10 @@
 <Project>
   <Import Project="$([MSBuild]::GetPathOfFileAbove('Directory.Build.targets', '$(MSBuildThisFileDirectory)../'))" />
+
+  <ItemGroup>
+    <!-- Deploy Microsoft.VisualStudio.SolutionPersistence next to the VS unit-test host. Shell.15.0 18.9.x references
+         it at runtime without declaring a NuGet dependency (it normally comes from the VS install), and the tests load
+         Shell.15.0 into a MEF catalog, so it must be copied locally. Scoped to test projects to keep it out of the VSIX. -->
+    <PackageReference Include="Microsoft.VisualStudio.SolutionPersistence" Version="$(MicrosoftVisualStudioSolutionPersistenceVersion)" PrivateAssets="all" ExcludeAssets="contentFiles;analyzers;native" />
+  </ItemGroup>
 </Project>