diff --git a/.github/workflows/build-and-test-BASE.yml b/.github/workflows/build-and-test-BASE.yml
index ccab0420a4..68ac678683 100644
--- a/.github/workflows/build-and-test-BASE.yml
+++ b/.github/workflows/build-and-test-BASE.yml
@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
-        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0]
+        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0, net9.0]
         include: 
           - os: ubuntu-latest
             args: "--filter TestCategory!=WindowsOnly"
@@ -40,6 +40,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     - name: Restore
       run: dotnet restore ${{ env.SOLUTION }}
diff --git a/.github/workflows/build-and-test-LOGGING.yml b/.github/workflows/build-and-test-LOGGING.yml
index 9ce794e976..8e4c0aefac 100644
--- a/.github/workflows/build-and-test-LOGGING.yml
+++ b/.github/workflows/build-and-test-LOGGING.yml
@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-latest]
-        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0]
+        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0, net9.0]
 
     steps:
     - uses: actions/checkout@v4
@@ -37,6 +37,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     - name: Restore
       run: dotnet restore ${{ env.SOLUTION }} 
diff --git a/.github/workflows/build-and-test-NETCORE.yml b/.github/workflows/build-and-test-NETCORE.yml
index dd094a9bba..f9f7ddee79 100644
--- a/.github/workflows/build-and-test-NETCORE.yml
+++ b/.github/workflows/build-and-test-NETCORE.yml
@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
-        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0]
+        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0, net9.0]
         include: 
           - os: ubuntu-latest
             args: "--filter TestCategory!=WindowsOnly"
@@ -40,6 +40,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     - name: Restore
       run: dotnet restore ${{ env.SOLUTION }}
diff --git a/.github/workflows/build-and-test-WEB.yml b/.github/workflows/build-and-test-WEB.yml
index 9f86bfdf54..300f30e059 100644
--- a/.github/workflows/build-and-test-WEB.yml
+++ b/.github/workflows/build-and-test-WEB.yml
@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-latest]
-        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0]
+        framework: [net452, net462, net472, net480, net481, netcoreapp3.1, net6.0, net7.0, net8.0, net9.0]
 
     steps:
     - uses: actions/checkout@v4
@@ -37,6 +37,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     - name: Restore
       run: dotnet restore ${{ env.SOLUTION }}
diff --git a/.github/workflows/codeql-csharp.yml b/.github/workflows/codeql-csharp.yml
index d0d1efa903..ac28cfe572 100644
--- a/.github/workflows/codeql-csharp.yml
+++ b/.github/workflows/codeql-csharp.yml
@@ -76,6 +76,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
diff --git a/.github/workflows/redfield-sanity-check.yml b/.github/workflows/redfield-sanity-check.yml
index 696bdb0264..3849ee7317 100644
--- a/.github/workflows/redfield-sanity-check.yml
+++ b/.github/workflows/redfield-sanity-check.yml
@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        framework: [netcoreapp3.1,net6.0,net7.0,net8.0]
+        framework: [netcoreapp3.1,net6.0,net7.0,net8.0,net9.0]
         include: 
             - os: ubuntu-latest
               args: "--filter TestCategory!=WindowsOnly"
@@ -40,6 +40,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     - name: Restore
       run: dotnet restore ${{ env.SOLUTION }}
diff --git a/.github/workflows/sanity.yml b/.github/workflows/sanity.yml
index 6d2f026c56..f04070e0c4 100644
--- a/.github/workflows/sanity.yml
+++ b/.github/workflows/sanity.yml
@@ -39,6 +39,7 @@ jobs:
             6.0.x
             7.0.x
             8.0.x
+            9.0.x
 
     - name: Restore
       run: dotnet restore ${{ matrix.solution }}
diff --git a/.props/Test.props b/.props/Test.props
index f80c0e89e3..085d85cf30 100644
--- a/.props/Test.props
+++ b/.props/Test.props
@@ -20,7 +20,7 @@
           - net7.0 (GA Nov 2022)
     -->
 
-    <SupportedFrameworks_NetCore>net8.0;net7.0;net6.0;netcoreapp3.1;</SupportedFrameworks_NetCore>
+    <SupportedFrameworks_NetCore>net9.0;net8.0;net7.0;net6.0;netcoreapp3.1;</SupportedFrameworks_NetCore>
     <SupportedFrameworks_NetFx Condition="$(OS) == 'Windows_NT'">net481;net480;net472;net462;</SupportedFrameworks_NetFx>
     <LegacyFrameworks_NetFx Condition="$(OS) == 'Windows_NT'">net46;net452;</LegacyFrameworks_NetFx>
     
diff --git a/Directory.Build.props b/Directory.Build.props
index da3949143b..77c427144d 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -82,8 +82,8 @@
     <LangVersion>preview</LangVersion>
 
     <IsNetFramework Condition="'$(TargetFramework)' == 'net452' Or '$(TargetFramework)' == 'net46' Or '$(TargetFramework)' == 'net461' Or '$(TargetFramework)' == 'net462' Or '$(TargetFramework)' == 'net472' Or '$(TargetFramework)' == 'net480' Or '$(TargetFramework)' == 'net481' ">True</IsNetFramework>
-    <IsNetCore Condition="'$(TargetFramework)' == 'netcoreapp3.1' Or '$(TargetFramework)' == 'net6.0' Or '$(TargetFramework)' == 'net7.0' Or '$(TargetFramework)' == 'net8.0'">True</IsNetCore>
-    <IsNetStandard20 Condition="'$(TargetFramework)' == 'net461' Or '$(TargetFramework)' == 'net462' Or '$(TargetFramework)' == 'net472' Or '$(TargetFramework)' == 'net480' Or '$(TargetFramework)' == 'net481' Or '$(TargetFramework)' == 'netcoreapp3.1' Or '$(TargetFramework)' == 'net6.0' Or '$(TargetFramework)' == 'net7.0' Or '$(TargetFramework)' == 'net8.0'">True</IsNetStandard20>
+    <IsNetCore Condition="'$(TargetFramework)' == 'netcoreapp3.1' Or '$(TargetFramework)' == 'net6.0' Or '$(TargetFramework)' == 'net7.0' Or '$(TargetFramework)' == 'net8.0' Or '$(TargetFramework)' == 'net9.0'">True</IsNetCore>
+    <IsNetStandard20 Condition="'$(TargetFramework)' == 'net461' Or '$(TargetFramework)' == 'net462' Or '$(TargetFramework)' == 'net472' Or '$(TargetFramework)' == 'net480' Or '$(TargetFramework)' == 'net481' Or '$(TargetFramework)' == 'netcoreapp3.1' Or '$(TargetFramework)' == 'net6.0' Or '$(TargetFramework)' == 'net7.0' Or '$(TargetFramework)' == 'net8.0' Or '$(TargetFramework)' == 'net9.0'">True</IsNetStandard20>
 
     <!-- .NET 6 introduces implicit global usings.
     This causes build errors in our multi-target projects.
diff --git a/NETCORE/test/IntegrationTests.Tests/IntegrationTests.Tests.csproj b/NETCORE/test/IntegrationTests.Tests/IntegrationTests.Tests.csproj
index dc66981a3e..06f1730f2d 100644
--- a/NETCORE/test/IntegrationTests.Tests/IntegrationTests.Tests.csproj
+++ b/NETCORE/test/IntegrationTests.Tests/IntegrationTests.Tests.csproj
@@ -31,6 +31,10 @@
     </None>
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'net9.0'">
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="[9.*-*,10.0)" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="[8.*-*,9.0)" />
   </ItemGroup>
diff --git a/WEB/Src/WindowsServer/WindowsServer.Tests/AppServicesHeartbeatTelemetryModuleTests.cs b/WEB/Src/WindowsServer/WindowsServer.Tests/AppServicesHeartbeatTelemetryModuleTests.cs
index 402cde8caf..935eea2974 100644
--- a/WEB/Src/WindowsServer/WindowsServer.Tests/AppServicesHeartbeatTelemetryModuleTests.cs
+++ b/WEB/Src/WindowsServer/WindowsServer.Tests/AppServicesHeartbeatTelemetryModuleTests.cs
@@ -143,7 +143,7 @@ private void RemoveTestEnvVarsAssociatedToModule(AppServicesHeartbeatTelemetryMo
         {
             foreach (var kvp in appServicesHbeatModule.WebHeartbeatPropertyNameEnvVarMap)
             {
-                Environment.SetEnvironmentVariable(kvp.Value, string.Empty);
+                Environment.SetEnvironmentVariable(kvp.Value, null);
             }
         }
     }