diff --git a/.github/workflows/csharp.yml b/.github/workflows/csharp.yml
index 1650a685..300016b8 100644
--- a/.github/workflows/csharp.yml
+++ b/.github/workflows/csharp.yml
@@ -29,7 +29,7 @@ jobs:
   netFrameworksAndUnitTest:
     name: Build Framework & Run Unit Tests
     needs: [ lintCodebase ]
-    runs-on: windows-2019 # required version for Framework 4.0
+    runs-on: windows-2022
     env:
       REPO_SLUG: ${{ github.repository }}
       BUILD_NUMBER: ${{ github.run_id }}
@@ -44,15 +44,51 @@ jobs:
         uses: microsoft/setup-msbuild@v1
       - name: Setup NuGet
         uses: NuGet/setup-nuget@v1
+      - name: Download and Extract .NET Framework Reference Assemblies
+        run: |
+          # Create temp directory
+          New-Item -ItemType Directory -Path "temp_ref_assemblies" -Force
+          
+          # Download .NET 4.0 Reference Assemblies
+          echo "Downloading .NET 4.0 Reference Assemblies..."
+          Invoke-WebRequest -Uri "https://www.nuget.org/api/v2/package/Microsoft.NETFramework.ReferenceAssemblies.net40/1.0.3" -OutFile "temp_ref_assemblies/net40_ref.zip"
+          
+          # Download .NET 4.5 Reference Assemblies  
+          echo "Downloading .NET 4.5 Reference Assemblies..."
+          Invoke-WebRequest -Uri "https://www.nuget.org/api/v2/package/Microsoft.NETFramework.ReferenceAssemblies.net45/1.0.3" -OutFile "temp_ref_assemblies/net45_ref.zip"
+          
+          # Extract .NET 4.0 Reference Assemblies
+          echo "Extracting .NET 4.0 Reference Assemblies..."
+          Expand-Archive -Path "temp_ref_assemblies/net40_ref.zip" -DestinationPath "temp_ref_assemblies/net40" -Force
+          if (Test-Path "temp_ref_assemblies/net40/build/.NETFramework/v4.0") {
+              echo "✓ .NET 4.0 Reference Assemblies extracted to workspace"
+          }
+          
+          # Extract .NET 4.5 Reference Assemblies
+          echo "Extracting .NET 4.5 Reference Assemblies..."
+          Expand-Archive -Path "temp_ref_assemblies/net45_ref.zip" -DestinationPath "temp_ref_assemblies/net45" -Force
+          if (Test-Path "temp_ref_assemblies/net45/build/.NETFramework/v4.5") {
+              echo "✓ .NET 4.5 Reference Assemblies extracted to workspace"
+          }
       - name: Restore NuGet packages
         run: nuget restore ./OptimizelySDK.NETFramework.sln
       - name: Build & strongly name assemblies
-        run: msbuild /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=$(pwd)/keypair.snk /p:Configuration=Release ./OptimizelySDK.NETFramework.sln
+        run: |
+          # Build with workspace-relative reference assembly paths
+          $Net40RefPath = "$(pwd)\temp_ref_assemblies\net40\build\.NETFramework\v4.0"
+          $Net45RefPath = "$(pwd)\temp_ref_assemblies\net45\build\.NETFramework\v4.5"
+          
+          echo "Using .NET 4.0 Reference Assemblies from: $Net40RefPath"
+          echo "Using .NET 4.5 Reference Assemblies from: $Net45RefPath"
+          
+          msbuild /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=$(pwd)/keypair.snk /p:Configuration=Release /p:FrameworkPathOverride="$Net45RefPath" ./OptimizelySDK.NETFramework.sln
       - name: Install & Run NUnit tests
         run: |
           nuget install NUnit.Console -Version 3.18.1 -DirectDownload -OutputDirectory .
           # https://docs.nunit.org/articles/nunit/running-tests/Console-Command-Line.html
           ./NUnit.ConsoleRunner.3.18.1\tools\nunit3-console.exe /timeout 10000 /process Separate ./OptimizelySDK.Tests/bin/Release/OptimizelySDK.Tests.dll
+      - name: Cleanup reference assemblies
+        run: Remove-Item -Path "temp_ref_assemblies" -Recurse -Force
   
   netStandard16:
     name: Build Standard 1.6
diff --git a/.github/workflows/csharp_release.yml b/.github/workflows/csharp_release.yml
index 80461161..f4c1736c 100644
--- a/.github/workflows/csharp_release.yml
+++ b/.github/workflows/csharp_release.yml
@@ -31,7 +31,7 @@ jobs:
   buildFrameworkVersions:
     name: Build Framework versions
     needs: [ variables ]
-    runs-on: windows-2019 # required version for Framework 4.0
+    runs-on: windows-2022
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -41,10 +41,46 @@ jobs:
         uses: microsoft/setup-msbuild@v2
       - name: Setup NuGet
         uses: nuget/setup-nuget@v2
+      - name: Download and Extract .NET Framework Reference Assemblies
+        run: |
+          # Create temp directory
+          New-Item -ItemType Directory -Path "temp_ref_assemblies" -Force
+          
+          # Download .NET 4.0 Reference Assemblies
+          echo "Downloading .NET 4.0 Reference Assemblies..."
+          Invoke-WebRequest -Uri "https://www.nuget.org/api/v2/package/Microsoft.NETFramework.ReferenceAssemblies.net40/1.0.3" -OutFile "temp_ref_assemblies/net40_ref.zip"
+          
+          # Download .NET 4.5 Reference Assemblies  
+          echo "Downloading .NET 4.5 Reference Assemblies..."
+          Invoke-WebRequest -Uri "https://www.nuget.org/api/v2/package/Microsoft.NETFramework.ReferenceAssemblies.net45/1.0.3" -OutFile "temp_ref_assemblies/net45_ref.zip"
+          
+          # Extract .NET 4.0 Reference Assemblies
+          echo "Extracting .NET 4.0 Reference Assemblies..."
+          Expand-Archive -Path "temp_ref_assemblies/net40_ref.zip" -DestinationPath "temp_ref_assemblies/net40" -Force
+          if (Test-Path "temp_ref_assemblies/net40/build/.NETFramework/v4.0") {
+              echo "✓ .NET 4.0 Reference Assemblies extracted to workspace"
+          }
+          
+          # Extract .NET 4.5 Reference Assemblies
+          echo "Extracting .NET 4.5 Reference Assemblies..."
+          Expand-Archive -Path "temp_ref_assemblies/net45_ref.zip" -DestinationPath "temp_ref_assemblies/net45" -Force
+          if (Test-Path "temp_ref_assemblies/net45/build/.NETFramework/v4.5") {
+              echo "✓ .NET 4.5 Reference Assemblies extracted to workspace"
+          }
       - name: Restore NuGet packages
         run: nuget restore ./OptimizelySDK.NETFramework.sln
       - name: Build and strongly name assemblies
-        run: msbuild /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=$(pwd)/keypair.snk /p:Configuration=Release ./OptimizelySDK.NETFramework.sln
+        run: |
+          # Build with workspace-relative reference assembly paths
+          $Net40RefPath = "$(pwd)\temp_ref_assemblies\net40\build\.NETFramework\v4.0"
+          $Net45RefPath = "$(pwd)\temp_ref_assemblies\net45\build\.NETFramework\v4.5"
+          
+          echo "Using .NET 4.0 Reference Assemblies from: $Net40RefPath"
+          echo "Using .NET 4.5 Reference Assemblies from: $Net45RefPath"
+          
+          msbuild /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=$(pwd)/keypair.snk /p:Configuration=Release /p:FrameworkPathOverride="$Net45RefPath" ./OptimizelySDK.NETFramework.sln
+      - name: Cleanup reference assemblies
+        run: Remove-Item -Path "temp_ref_assemblies" -Recurse -Force
       - name: Upload Framework artifacts
         uses: actions/upload-artifact@v4
         with:
@@ -55,7 +91,7 @@ jobs:
   buildStandard16:
     name: Build Standard 1.6 version
     needs: [ variables ]
-    runs-on: windows-latest
+    runs-on: windows-2022
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -77,7 +113,7 @@ jobs:
   buildStandard20:
     name: Build Standard 2.0 version
     needs: [ variables ]
-    runs-on: windows-latest
+    runs-on: windows-2022
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
diff --git a/.github/workflows/sonarqube.yml b/.github/workflows/sonarqube.yml
deleted file mode 100644
index 54ba8165..00000000
--- a/.github/workflows/sonarqube.yml
+++ /dev/null
@@ -1,45 +0,0 @@
-name: SonarQube
-on:
-  push:
-    branches:
-      - dsier/sonarqube
-jobs:
-  build:
-    name: Build
-    runs-on: windows-latest
-    steps:
-      - name: Set up JDK 11
-        uses: actions/setup-java@v4
-        with:
-          java-version: 1.11
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-      - name: Cache SonarCloud packages
-        uses: actions/cache@v4
-        with:
-          path: ~\sonar\cache
-          key: ${{ runner.os }}-sonar
-          restore-keys: ${{ runner.os }}-sonar
-      - name: Cache SonarCloud scanner
-        id: cache-sonar-scanner
-        uses: actions/cache@v4
-        with:
-          path: .\.sonar\scanner
-          key: ${{ runner.os }}-sonar-scanner
-          restore-keys: ${{ runner.os }}-sonar-scanner
-      - name: Install SonarCloud scanner
-        if: steps.cache-sonar-scanner.outputs.cache-hit != 'true'
-        shell: powershell
-        run: |
-          New-Item -Path .\.sonar\scanner -ItemType Directory
-          dotnet tool update dotnet-sonarscanner --tool-path .\.sonar\scanner
-      - name: Build and analyze
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}  # Needed to get PR information, if any
-          SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
-        shell: powershell
-        run: |
-          .\.sonar\scanner\dotnet-sonarscanner begin /k:"csharpsdk" /o:"optidevx" /d:sonar.login="${{ secrets.SONAR_TOKEN }}" /d:sonar.host.url="https://sonarcloud.io"
-          dotnet build .\OptimizelySDK\
-          .\.sonar\scanner\dotnet-sonarscanner end /d:sonar.login="${{ secrets.SONAR_TOKEN