diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index decbbc1269..336d144c6a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -52,7 +52,7 @@ jobs:
       with:
         dotnet-version: |
           6.0.x
-          7.0.x
+          8.0.x
 
     - name: Setup .NET SDK
       uses: actions/setup-dotnet@6bd8b7f7774af54e05809fcc5431931b3eb1ddee # v4.0.1
diff --git a/Directory.Build.props b/Directory.Build.props
index 653865f40e..b13ec1f038 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -20,18 +20,12 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
     <NeutralLanguage>en-US</NeutralLanguage>
     <!--
-    TODO Remove deprecated TFMs
-    -->
-    <CheckEolTargetFramework>false</CheckEolTargetFramework>
-    <NoWarn>$(NoWarn);NETSDK1138</NoWarn>
-    <!--
-    TODO Update packages to resolve vulnerability warnings
-    -->
-    <NoWarn>$(NoWarn);NU1902;NU1903</NoWarn>
-    <!--
     TODO Fix warning from Swashbuckle.AspNetCore with dotnet pack
     -->
     <NoWarn>$(NoWarn);NU5128</NoWarn>
+    <!-- TODO Remove once .NET 9.0.0 is released -->
+    <NoWarn>$(NoWarn);NU5104</NoWarn>
+    <NuGetAuditMode>direct</NuGetAuditMode>
     <!--
     TODO Go through the code and add nullable annotations
     <Nullable>enable</Nullable>
@@ -49,7 +43,7 @@
     <SymbolPackageFormat>snupkg</SymbolPackageFormat>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <UseArtifactsOutput>true</UseArtifactsOutput>
-    <VersionPrefix>6.7.1</VersionPrefix>
+    <VersionPrefix>7.0.0</VersionPrefix>
     <WarnOnPackingNonPackableProject>false</WarnOnPackingNonPackableProject>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(GITHUB_ACTIONS)' != '' ">
diff --git a/global.json b/global.json
index 1668e88eb0..76f24e30c8 100644
--- a/global.json
+++ b/global.json
@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.303",
+    "version": "9.0.100-preview.6.24328.19",
     "allowPrerelease": false,
     "rollForward": "latestMajor"
   }
diff --git a/src/Swashbuckle.AspNetCore.Annotations/Swashbuckle.AspNetCore.Annotations.csproj b/src/Swashbuckle.AspNetCore.Annotations/Swashbuckle.AspNetCore.Annotations.csproj
index 80765f99f3..94c64a46b2 100644
--- a/src/Swashbuckle.AspNetCore.Annotations/Swashbuckle.AspNetCore.Annotations.csproj
+++ b/src/Swashbuckle.AspNetCore.Annotations/Swashbuckle.AspNetCore.Annotations.csproj
@@ -8,7 +8,7 @@
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore;annotations</PackageTags>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Swashbuckle.AspNetCore.ApiTesting.Xunit/Swashbuckle.AspNetCore.ApiTesting.Xunit.csproj b/src/Swashbuckle.AspNetCore.ApiTesting.Xunit/Swashbuckle.AspNetCore.ApiTesting.Xunit.csproj
index b20ff1cfa4..0cfacfca94 100644
--- a/src/Swashbuckle.AspNetCore.ApiTesting.Xunit/Swashbuckle.AspNetCore.ApiTesting.Xunit.csproj
+++ b/src/Swashbuckle.AspNetCore.ApiTesting.Xunit/Swashbuckle.AspNetCore.ApiTesting.Xunit.csproj
@@ -7,7 +7,7 @@
     <IsTestProject>false</IsTestProject>
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;openapi;test-first;spec-first;testing;aspnetcore;xunit</PackageTags>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Swashbuckle.AspNetCore.ApiTesting/Swashbuckle.AspNetCore.ApiTesting.csproj b/src/Swashbuckle.AspNetCore.ApiTesting/Swashbuckle.AspNetCore.ApiTesting.csproj
index dc86ee5cc5..0e399942d7 100644
--- a/src/Swashbuckle.AspNetCore.ApiTesting/Swashbuckle.AspNetCore.ApiTesting.csproj
+++ b/src/Swashbuckle.AspNetCore.ApiTesting/Swashbuckle.AspNetCore.ApiTesting.csproj
@@ -6,7 +6,7 @@
     <IsPackable>true</IsPackable>
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;openapi;test-first;spec-first;testing;aspnetcore</PackageTags>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -16,29 +16,21 @@
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="2.1.2" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp3.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="3.0.0" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net5.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="5.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="2.1.3" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net6.0' ">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="6.0.0" />
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net7.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="7.0.0" />
-  </ItemGroup>
-
   <ItemGroup Condition=" '$(TargetFramework)' == 'net8.0' ">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="8.0.0" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net9.0' ">
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="9.0.0-preview.6.24328.4" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" PrivateAssets="All" />
     <AdditionalFiles Include="PublicAPI\PublicAPI.Shipped.txt" />
diff --git a/src/Swashbuckle.AspNetCore.Cli/HostingApplication.cs b/src/Swashbuckle.AspNetCore.Cli/HostingApplication.cs
index 3c7685c088..4dfe6680d5 100644
--- a/src/Swashbuckle.AspNetCore.Cli/HostingApplication.cs
+++ b/src/Swashbuckle.AspNetCore.Cli/HostingApplication.cs
@@ -4,9 +4,7 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Http.Features;
-#if NETCOREAPP3_0_OR_GREATER
 using Microsoft.Extensions.DependencyInjection;
-#endif
 using Microsoft.Extensions.Hosting;
 
 namespace Swashbuckle.AspNetCore.Cli
@@ -19,9 +17,6 @@ internal class HostingApplication
     {
         internal static IServiceProvider GetServiceProvider(Assembly assembly)
         {
-#if NETCOREAPP2_1
-            return null;
-#else
             // We're disabling the default server and the console host lifetime. This will disable:
             // 1. Listening on ports
             // 2. Logging to the console from the default host.
@@ -102,7 +97,6 @@ void OnEntryPointExit(Exception exception)
             }
 
             return null;
-#endif
         }
 
         private class NoopHostLifetime : IHostLifetime
diff --git a/src/Swashbuckle.AspNetCore.Cli/Swashbuckle.AspNetCore.Cli.csproj b/src/Swashbuckle.AspNetCore.Cli/Swashbuckle.AspNetCore.Cli.csproj
index 26c75da3cb..2f1fb6fe5c 100644
--- a/src/Swashbuckle.AspNetCore.Cli/Swashbuckle.AspNetCore.Cli.csproj
+++ b/src/Swashbuckle.AspNetCore.Cli/Swashbuckle.AspNetCore.Cli.csproj
@@ -7,7 +7,7 @@
     <OutputType>Exe</OutputType>
     <PackAsTool>true</PackAsTool>
     <PackageId>Swashbuckle.AspNetCore.Cli</PackageId>
-    <TargetFrameworks>netcoreapp2.1;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <ToolCommandName>swagger</ToolCommandName>
   </PropertyGroup>
 
@@ -15,8 +15,4 @@
     <ProjectReference Include="..\Swashbuckle.AspNetCore.Swagger\Swashbuckle.AspNetCore.Swagger.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
-    <PackageReference Include="Microsoft.AspNetCore" />
-  </ItemGroup>
-
 </Project>
diff --git a/src/Swashbuckle.AspNetCore.Newtonsoft/Swashbuckle.AspNetCore.Newtonsoft.csproj b/src/Swashbuckle.AspNetCore.Newtonsoft/Swashbuckle.AspNetCore.Newtonsoft.csproj
index 13fd76f336..b98a1cd4f3 100644
--- a/src/Swashbuckle.AspNetCore.Newtonsoft/Swashbuckle.AspNetCore.Newtonsoft.csproj
+++ b/src/Swashbuckle.AspNetCore.Newtonsoft/Swashbuckle.AspNetCore.Newtonsoft.csproj
@@ -6,7 +6,7 @@
     <IsPackable>true</IsPackable>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore;newtonsoft</PackageTags>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -17,26 +17,18 @@
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Formatters.Json" />
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp3.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" VersionOverride="3.0.0" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net5.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" VersionOverride="5.0.0" />
-  </ItemGroup>
-
   <ItemGroup Condition=" '$(TargetFramework)' == 'net6.0' ">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" VersionOverride="6.0.0" />
   </ItemGroup>
 
-   <ItemGroup Condition=" '$(TargetFramework)' == 'net7.0' ">
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" VersionOverride="7.0.0" />
-  </ItemGroup>
-
   <ItemGroup Condition=" '$(TargetFramework)' == 'net8.0' ">
     <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" VersionOverride="8.0.0" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net9.0' ">
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" VersionOverride="9.0.0-preview.6.24328.4" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" PrivateAssets="All" />
     <AdditionalFiles Include="PublicAPI\PublicAPI.Shipped.txt" />
diff --git a/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj b/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj
index e9357695b5..f5b11a0ed0 100644
--- a/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj
+++ b/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj
@@ -8,7 +8,7 @@
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore;redoc</PackageTags>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Swashbuckle.AspNetCore.Swagger/Swashbuckle.AspNetCore.Swagger.csproj b/src/Swashbuckle.AspNetCore.Swagger/Swashbuckle.AspNetCore.Swagger.csproj
index 801dc9e216..9985101a28 100644
--- a/src/Swashbuckle.AspNetCore.Swagger/Swashbuckle.AspNetCore.Swagger.csproj
+++ b/src/Swashbuckle.AspNetCore.Swagger/Swashbuckle.AspNetCore.Swagger.csproj
@@ -8,7 +8,7 @@
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore</PackageTags>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
   <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
     <EnableAotAnalyzer>true</EnableAotAnalyzer>
diff --git a/src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureSwaggerGeneratorOptions.cs b/src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureSwaggerGeneratorOptions.cs
index 29d43ca555..9c801ccaaa 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureSwaggerGeneratorOptions.cs
+++ b/src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureSwaggerGeneratorOptions.cs
@@ -6,7 +6,7 @@
 using Microsoft.Extensions.Options;
 using Microsoft.OpenApi.Models;
 
-#if NETSTANDARD2_0
+#if NETSTANDARD
 using IWebHostEnvironment = Microsoft.AspNetCore.Hosting.IHostingEnvironment;
 #endif
 
diff --git a/src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/SchemaGenerator.cs b/src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/SchemaGenerator.cs
index 89df6d7cc1..108cfa4894 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/SchemaGenerator.cs
+++ b/src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/SchemaGenerator.cs
@@ -212,7 +212,7 @@ private OpenApiSchema GeneratePolymorphicSchema(
             typeof(IFormFile),
             typeof(FileResult),
             typeof(System.IO.Stream),
-#if NETCOREAPP3_0_OR_GREATER
+#if !NETSTANDARD
             typeof(System.IO.Pipelines.PipeReader),
 #endif
         ];
diff --git a/src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/ApiParameterDescriptionExtensions.cs b/src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/ApiParameterDescriptionExtensions.cs
index e505905e60..a36ed4c778 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/ApiParameterDescriptionExtensions.cs
+++ b/src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/ApiParameterDescriptionExtensions.cs
@@ -49,7 +49,7 @@ public static bool IsRequiredParameter(this ApiParameterDescription apiParameter
 
             // For non-controllers, prefer the IsRequired flag if we're not on netstandard 2.0, otherwise fallback to the default logic.
             return
-#if !NETSTANDARD2_0
+#if !NETSTANDARD
             apiParameter.IsRequired;
 #else
             IsRequired();
@@ -59,7 +59,7 @@ public static bool IsRequiredParameter(this ApiParameterDescription apiParameter
         public static ParameterInfo ParameterInfo(this ApiParameterDescription apiParameter)
         {
             var parameterDescriptor = apiParameter.ParameterDescriptor as
-#if NETCOREAPP2_2_OR_GREATER
+#if !NETSTANDARD
                 Microsoft.AspNetCore.Mvc.Infrastructure.IParameterInfoParameterDescriptor;
 #else
                 ControllerParameterDescriptor;
diff --git a/src/Swashbuckle.AspNetCore.SwaggerGen/Swashbuckle.AspNetCore.SwaggerGen.csproj b/src/Swashbuckle.AspNetCore.SwaggerGen/Swashbuckle.AspNetCore.SwaggerGen.csproj
index 43392c1ebb..1393f618ae 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerGen/Swashbuckle.AspNetCore.SwaggerGen.csproj
+++ b/src/Swashbuckle.AspNetCore.SwaggerGen/Swashbuckle.AspNetCore.SwaggerGen.csproj
@@ -8,7 +8,7 @@
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore</PackageTags>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIBuilderExtensions.cs b/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIBuilderExtensions.cs
index 0ca25662de..e366fa318f 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIBuilderExtensions.cs
+++ b/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIBuilderExtensions.cs
@@ -4,7 +4,7 @@
 using Microsoft.Extensions.Options;
 using Swashbuckle.AspNetCore.SwaggerUI;
 
-#if NETSTANDARD2_0
+#if NETSTANDARD
 using IWebHostEnvironment = Microsoft.AspNetCore.Hosting.IHostingEnvironment;
 #endif
 
diff --git a/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIMiddleware.cs b/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIMiddleware.cs
index d89129d8c1..6f8d89a357 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIMiddleware.cs
+++ b/src/Swashbuckle.AspNetCore.SwaggerUI/SwaggerUIMiddleware.cs
@@ -16,7 +16,7 @@
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
-#if NETSTANDARD2_0
+#if NETSTANDARD
 using IWebHostEnvironment = Microsoft.AspNetCore.Hosting.IHostingEnvironment;
 #endif
 
diff --git a/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj b/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj
index 1eb5faa1b6..20a6ef35a2 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj
+++ b/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj
@@ -8,7 +8,7 @@
     <NoWarn>$(NoWarn);1591</NoWarn>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore</PackageTags>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
   <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
     <EnableAotAnalyzer>true</EnableAotAnalyzer>
diff --git a/src/Swashbuckle.AspNetCore/Swashbuckle.AspNetCore.csproj b/src/Swashbuckle.AspNetCore/Swashbuckle.AspNetCore.csproj
index 1a85c1f37e..96b2a604dd 100644
--- a/src/Swashbuckle.AspNetCore/Swashbuckle.AspNetCore.csproj
+++ b/src/Swashbuckle.AspNetCore/Swashbuckle.AspNetCore.csproj
@@ -13,7 +13,15 @@
     <NuspecFile>$(MSBuildProjectName).nuspec</NuspecFile>
     <PackageId>Swashbuckle.AspNetCore</PackageId>
     <PackageTags>swagger;documentation;discovery;help;webapi;aspnet;aspnetcore</PackageTags>
-    <TargetFrameworks>netstandard2.0;netcoreapp3.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net9.0</TargetFrameworks>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net8.0' ">
+    <MicrosoftExtensionsApiDescriptionServerPackageVersion>8.0.0</MicrosoftExtensionsApiDescriptionServerPackageVersion>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net9.0' ">
+    <MicrosoftExtensionsApiDescriptionServerPackageVersion>9.0.0-preview.6.24328.4</MicrosoftExtensionsApiDescriptionServerPackageVersion>
   </PropertyGroup>
 
   <Target Name="PopulateNuspec">
diff --git a/test/Swashbuckle.AspNetCore.Annotations.Test/Swashbuckle.AspNetCore.Annotations.Test.csproj b/test/Swashbuckle.AspNetCore.Annotations.Test/Swashbuckle.AspNetCore.Annotations.Test.csproj
index 9db709d6b1..d070abc7e8 100644
--- a/test/Swashbuckle.AspNetCore.Annotations.Test/Swashbuckle.AspNetCore.Annotations.Test.csproj
+++ b/test/Swashbuckle.AspNetCore.Annotations.Test/Swashbuckle.AspNetCore.Annotations.Test.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/Swashbuckle.AspNetCore.ApiTesting.Test/Swashbuckle.AspNetCore.ApiTesting.Test.csproj b/test/Swashbuckle.AspNetCore.ApiTesting.Test/Swashbuckle.AspNetCore.ApiTesting.Test.csproj
index 55d738e426..e6b3ab60f3 100644
--- a/test/Swashbuckle.AspNetCore.ApiTesting.Test/Swashbuckle.AspNetCore.ApiTesting.Test.csproj
+++ b/test/Swashbuckle.AspNetCore.ApiTesting.Test/Swashbuckle.AspNetCore.ApiTesting.Test.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/Swashbuckle.AspNetCore.Cli.Test/Swashbuckle.AspNetCore.Cli.Test.csproj b/test/Swashbuckle.AspNetCore.Cli.Test/Swashbuckle.AspNetCore.Cli.Test.csproj
index 66198fe569..e88a366f4d 100644
--- a/test/Swashbuckle.AspNetCore.Cli.Test/Swashbuckle.AspNetCore.Cli.Test.csproj
+++ b/test/Swashbuckle.AspNetCore.Cli.Test/Swashbuckle.AspNetCore.Cli.Test.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/Swashbuckle.AspNetCore.IntegrationTests/Swashbuckle.AspNetCore.IntegrationTests.csproj b/test/Swashbuckle.AspNetCore.IntegrationTests/Swashbuckle.AspNetCore.IntegrationTests.csproj
index 8390f7df37..92f1434bc4 100644
--- a/test/Swashbuckle.AspNetCore.IntegrationTests/Swashbuckle.AspNetCore.IntegrationTests.csproj
+++ b/test/Swashbuckle.AspNetCore.IntegrationTests/Swashbuckle.AspNetCore.IntegrationTests.csproj
@@ -4,7 +4,7 @@
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)..\..\src\Swashbuckle.AspNetCore.Swagger\Swashbuckle.AspNetCore.Swagger.snk</AssemblyOriginatorKeyFile>
     <NoWarn>$(NoWarn);8002</NoWarn>
     <SignAssembly>true</SignAssembly>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -38,8 +38,13 @@
   </ItemGroup>
 
   <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">
-    <PackageReference Update="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="8.0.4" />
-    <PackageReference Update="Microsoft.AspNetCore.TestHost" VersionOverride="8.0.4" />
+    <PackageReference Update="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="8.0.7" />
+    <PackageReference Update="Microsoft.AspNetCore.TestHost" VersionOverride="8.0.7" />
+  </ItemGroup>
+
+  <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net9.0'))">
+    <PackageReference Update="Microsoft.AspNetCore.Mvc.Testing" VersionOverride="9.0.0-preview.6.24328.4" />
+    <PackageReference Update="Microsoft.AspNetCore.TestHost" VersionOverride="9.0.0-preview.6.24328.4" />
   </ItemGroup>
 
 </Project>
diff --git a/test/Swashbuckle.AspNetCore.Newtonsoft.Test/Swashbuckle.AspNetCore.Newtonsoft.Test.csproj b/test/Swashbuckle.AspNetCore.Newtonsoft.Test/Swashbuckle.AspNetCore.Newtonsoft.Test.csproj
index 30844cfedb..76518e5855 100644
--- a/test/Swashbuckle.AspNetCore.Newtonsoft.Test/Swashbuckle.AspNetCore.Newtonsoft.Test.csproj
+++ b/test/Swashbuckle.AspNetCore.Newtonsoft.Test/Swashbuckle.AspNetCore.Newtonsoft.Test.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/Swashbuckle.AspNetCore.SwaggerGen.Test/Swashbuckle.AspNetCore.SwaggerGen.Test.csproj b/test/Swashbuckle.AspNetCore.SwaggerGen.Test/Swashbuckle.AspNetCore.SwaggerGen.Test.csproj
index 950eefb2fa..3661661514 100644
--- a/test/Swashbuckle.AspNetCore.SwaggerGen.Test/Swashbuckle.AspNetCore.SwaggerGen.Test.csproj
+++ b/test/Swashbuckle.AspNetCore.SwaggerGen.Test/Swashbuckle.AspNetCore.SwaggerGen.Test.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>1701;1702;1591</NoWarn>
-    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <SignAssembly>True</SignAssembly>
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)..\..\src\Swashbuckle.AspNetCore.Swagger\Swashbuckle.AspNetCore.Swagger.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>
diff --git a/test/Swashbuckle.AspNetCore.TestSupport/ApiExplorer/ApiDescriptionFactory.cs b/test/Swashbuckle.AspNetCore.TestSupport/ApiExplorer/ApiDescriptionFactory.cs
index 67f4e869ee..338f8695d3 100644
--- a/test/Swashbuckle.AspNetCore.TestSupport/ApiExplorer/ApiDescriptionFactory.cs
+++ b/test/Swashbuckle.AspNetCore.TestSupport/ApiExplorer/ApiDescriptionFactory.cs
@@ -39,11 +39,7 @@ public static ApiDescription Create(
                         .FirstOrDefault(parameterDescriptor => parameterDescriptor.Name == parameter.Name);
 
                     var parameterDescriptorWithParameterInfo = parameter.ParameterDescriptor as
-#if NETCOREAPP2_2_OR_GREATER
                         Microsoft.AspNetCore.Mvc.Infrastructure.IParameterInfoParameterDescriptor;
-#else
-                        ControllerParameterDescriptor;
-#endif
 
                     if (parameterDescriptorWithParameterInfo != null && parameter.ModelMetadata == null)
                     {
diff --git a/test/Swashbuckle.AspNetCore.TestSupport/Swashbuckle.AspNetCore.TestSupport.csproj b/test/Swashbuckle.AspNetCore.TestSupport/Swashbuckle.AspNetCore.TestSupport.csproj
index 4fd2d10b91..a5748479e8 100644
--- a/test/Swashbuckle.AspNetCore.TestSupport/Swashbuckle.AspNetCore.TestSupport.csproj
+++ b/test/Swashbuckle.AspNetCore.TestSupport/Swashbuckle.AspNetCore.TestSupport.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <IsPackable>false</IsPackable>
     <IsTestProject>false</IsTestProject>
     <VersionPrefix>1.0.0</VersionPrefix>
diff --git a/test/WebSites/Basic/Basic.csproj b/test/WebSites/Basic/Basic.csproj
index dd55d219f3..37719f94eb 100644
--- a/test/WebSites/Basic/Basic.csproj
+++ b/test/WebSites/Basic/Basic.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>$(NoWarn);1591</NoWarn>
-    <TargetFrameworks>netcoreapp3.1;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/CliExample/CliExample.csproj b/test/WebSites/CliExample/CliExample.csproj
index 59092cc3b7..013d8254ae 100644
--- a/test/WebSites/CliExample/CliExample.csproj
+++ b/test/WebSites/CliExample/CliExample.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <DotNetSwaggerPath>$([System.IO.Path]::Combine('$(ArtifactsPath)', 'bin', 'Swashbuckle.AspNetCore.Cli', '$(Configuration.ToLower())_$(TargetFramework)'))</DotNetSwaggerPath>
   </PropertyGroup>
 
diff --git a/test/WebSites/CliExample/wwwroot/swagger/v1/swagger_net9.0.json b/test/WebSites/CliExample/wwwroot/swagger/v1/swagger_net9.0.json
new file mode 100644
index 0000000000..0e1dee7edd
--- /dev/null
+++ b/test/WebSites/CliExample/wwwroot/swagger/v1/swagger_net9.0.json
@@ -0,0 +1,54 @@
+{
+  "openapi": "3.0.1",
+  "info": {
+    "title": "CliExample",
+    "version": "1.0"
+  },
+  "servers": [
+    {
+      "url": "http://localhost:51071"
+    }
+  ],
+  "paths": {
+    "/products": {
+      "get": {
+        "tags": [
+          "Products"
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "array",
+                  "items": {
+                    "$ref": "#/components/schemas/Product"
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "Product": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "description": {
+            "type": "string",
+            "nullable": true
+          }
+        },
+        "additionalProperties": false
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/test/WebSites/CliExampleWithFactory/CliExampleWithFactory.csproj b/test/WebSites/CliExampleWithFactory/CliExampleWithFactory.csproj
index 154b9d9f30..9a1b016761 100644
--- a/test/WebSites/CliExampleWithFactory/CliExampleWithFactory.csproj
+++ b/test/WebSites/CliExampleWithFactory/CliExampleWithFactory.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <DotNetSwaggerPath>$([System.IO.Path]::Combine('$(ArtifactsPath)', 'bin', 'Swashbuckle.AspNetCore.Cli', '$(Configuration.ToLower())_$(TargetFramework)'))</DotNetSwaggerPath>
   </PropertyGroup>
 
diff --git a/test/WebSites/CliExampleWithFactory/wwwroot/swagger/v1/swagger_net9.0.json b/test/WebSites/CliExampleWithFactory/wwwroot/swagger/v1/swagger_net9.0.json
new file mode 100644
index 0000000000..2778aed45a
--- /dev/null
+++ b/test/WebSites/CliExampleWithFactory/wwwroot/swagger/v1/swagger_net9.0.json
@@ -0,0 +1,54 @@
+{
+  "openapi": "3.0.1",
+  "info": {
+    "title": "CliExampleWithFactory",
+    "version": "1.0"
+  },
+  "servers": [
+    {
+      "url": "http://localhost:57556/"
+    }
+  ],
+  "paths": {
+    "/products": {
+      "get": {
+        "tags": [
+          "Products"
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "array",
+                  "items": {
+                    "$ref": "#/components/schemas/Product"
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "Product": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "description": {
+            "type": "string",
+            "nullable": true
+          }
+        },
+        "additionalProperties": false
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/test/WebSites/ConfigFromFile/ConfigFromFile.csproj b/test/WebSites/ConfigFromFile/ConfigFromFile.csproj
index c15a19becf..2728cf8caf 100644
--- a/test/WebSites/ConfigFromFile/ConfigFromFile.csproj
+++ b/test/WebSites/ConfigFromFile/ConfigFromFile.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/CustomDocumentSerializer/CustomDocumentSerializer.csproj b/test/WebSites/CustomDocumentSerializer/CustomDocumentSerializer.csproj
index 997a07e351..140eef808f 100644
--- a/test/WebSites/CustomDocumentSerializer/CustomDocumentSerializer.csproj
+++ b/test/WebSites/CustomDocumentSerializer/CustomDocumentSerializer.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <DotNetSwaggerPath>$([System.IO.Path]::Combine('$(ArtifactsPath)', 'bin', 'Swashbuckle.AspNetCore.Cli', '$(Configuration)_$(TargetFramework)', 'dotnet-swagger.dll'))</DotNetSwaggerPath>
diff --git a/test/WebSites/CustomUIConfig/CustomUIConfig.csproj b/test/WebSites/CustomUIConfig/CustomUIConfig.csproj
index 12c1652b3c..3a8a17dd3b 100644
--- a/test/WebSites/CustomUIConfig/CustomUIConfig.csproj
+++ b/test/WebSites/CustomUIConfig/CustomUIConfig.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/CustomUIIndex/CustomUIIndex.csproj b/test/WebSites/CustomUIIndex/CustomUIIndex.csproj
index 0915fc16fa..34c5e70e24 100644
--- a/test/WebSites/CustomUIIndex/CustomUIIndex.csproj
+++ b/test/WebSites/CustomUIIndex/CustomUIIndex.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/GenericControllers/GenericControllers.csproj b/test/WebSites/GenericControllers/GenericControllers.csproj
index 5127c90d20..6c46b64a1d 100644
--- a/test/WebSites/GenericControllers/GenericControllers.csproj
+++ b/test/WebSites/GenericControllers/GenericControllers.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>$(NoWarn);1591</NoWarn>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/MinimalApp/MinimalApp.csproj b/test/WebSites/MinimalApp/MinimalApp.csproj
index 997a07e351..140eef808f 100644
--- a/test/WebSites/MinimalApp/MinimalApp.csproj
+++ b/test/WebSites/MinimalApp/MinimalApp.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <DotNetSwaggerPath>$([System.IO.Path]::Combine('$(ArtifactsPath)', 'bin', 'Swashbuckle.AspNetCore.Cli', '$(Configuration)_$(TargetFramework)', 'dotnet-swagger.dll'))</DotNetSwaggerPath>
diff --git a/test/WebSites/MinimalAppWithHostedServices/MinimalAppWithHostedServices.csproj b/test/WebSites/MinimalAppWithHostedServices/MinimalAppWithHostedServices.csproj
index 88afa5f5a3..72d679fbf7 100644
--- a/test/WebSites/MinimalAppWithHostedServices/MinimalAppWithHostedServices.csproj
+++ b/test/WebSites/MinimalAppWithHostedServices/MinimalAppWithHostedServices.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <DotNetSwaggerPath>$([System.IO.Path]::Combine('$(ArtifactsPath)', 'bin', 'Swashbuckle.AspNetCore.Cli', '$(Configuration)_$(TargetFramework)', 'dotnet-swagger.dll'))</DotNetSwaggerPath>
diff --git a/test/WebSites/MultipleVersions/MultipleVersions.csproj b/test/WebSites/MultipleVersions/MultipleVersions.csproj
index 93ff61a200..c844490d94 100644
--- a/test/WebSites/MultipleVersions/MultipleVersions.csproj
+++ b/test/WebSites/MultipleVersions/MultipleVersions.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/MvcWithNullable/MvcWithNullable.csproj b/test/WebSites/MvcWithNullable/MvcWithNullable.csproj
index 29f5a084a3..552207474c 100644
--- a/test/WebSites/MvcWithNullable/MvcWithNullable.csproj
+++ b/test/WebSites/MvcWithNullable/MvcWithNullable.csproj
@@ -5,7 +5,7 @@
     <NoWarn>$(NoWarn);CA1050</NoWarn>
     <Nullable>enable</Nullable>
     <RootNamespace>WebApi</RootNamespace>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/NswagClientExample/NswagClientExample.csproj b/test/WebSites/NswagClientExample/NswagClientExample.csproj
index 4ee15c17f8..fac4a2a7e4 100644
--- a/test/WebSites/NswagClientExample/NswagClientExample.csproj
+++ b/test/WebSites/NswagClientExample/NswagClientExample.csproj
@@ -1,10 +1,13 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <DotNetSwaggerPath>$([System.IO.Path]::Combine('$(ArtifactsPath)', 'bin', 'Swashbuckle.AspNetCore.Cli', '$(Configuration.ToLower())_$(TargetFramework)'))</DotNetSwaggerPath>
     <_NSwagTool>$(NSwagExe_Net60)</_NSwagTool>
     <_NSwagTool Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">$(NSwagExe_Net80)</_NSwagTool>
+    <!--
+    <_NSwagTool Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net9.0'))">$(NSwagExe_Net90)</_NSwagTool>
+    -->
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/NswagClientExample/swagger_net9.0.json b/test/WebSites/NswagClientExample/swagger_net9.0.json
new file mode 100644
index 0000000000..68e90e3375
--- /dev/null
+++ b/test/WebSites/NswagClientExample/swagger_net9.0.json
@@ -0,0 +1,140 @@
+{
+  "openapi": "3.0.1",
+  "info": {
+    "title": "NswagClientExample",
+    "version": "1.0"
+  },
+  "servers": [
+    {
+      "url": "http://example.com"
+    }
+  ],
+  "paths": {
+    "/Animals": {
+      "post": {
+        "tags": [
+          "Animals"
+        ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "oneOf": [
+                  {
+                    "$ref": "#/components/schemas/Animal"
+                  },
+                  {
+                    "$ref": "#/components/schemas/Cat"
+                  },
+                  {
+                    "$ref": "#/components/schemas/Dog"
+                  }
+                ]
+              }
+            },
+            "text/json": {
+              "schema": {
+                "oneOf": [
+                  {
+                    "$ref": "#/components/schemas/Animal"
+                  },
+                  {
+                    "$ref": "#/components/schemas/Cat"
+                  },
+                  {
+                    "$ref": "#/components/schemas/Dog"
+                  }
+                ]
+              }
+            },
+            "application/*+json": {
+              "schema": {
+                "oneOf": [
+                  {
+                    "$ref": "#/components/schemas/Animal"
+                  },
+                  {
+                    "$ref": "#/components/schemas/Cat"
+                  },
+                  {
+                    "$ref": "#/components/schemas/Dog"
+                  }
+                ]
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "OK"
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "Animal": {
+        "required": [
+          "animalType"
+        ],
+        "type": "object",
+        "properties": {
+          "animalType": {
+            "$ref": "#/components/schemas/AnimalType"
+          }
+        },
+        "additionalProperties": false,
+        "discriminator": {
+          "propertyName": "animalType",
+          "mapping": {
+            "Cat": "#/components/schemas/Cat",
+            "Dog": "#/components/schemas/Dog"
+          }
+        }
+      },
+      "AnimalType": {
+        "enum": [
+          "Cat",
+          "Dog"
+        ],
+        "type": "string"
+      },
+      "Cat": {
+        "allOf": [
+          {
+            "$ref": "#/components/schemas/Animal"
+          },
+          {
+            "type": "object",
+            "properties": {
+              "catSpecificProperty": {
+                "type": "string",
+                "nullable": true
+              }
+            },
+            "additionalProperties": false
+          }
+        ]
+      },
+      "Dog": {
+        "allOf": [
+          {
+            "$ref": "#/components/schemas/Animal"
+          },
+          {
+            "type": "object",
+            "properties": {
+              "dogSpecificProperty": {
+                "type": "string",
+                "nullable": true
+              }
+            },
+            "additionalProperties": false
+          }
+        ]
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/test/WebSites/OAuth2Integration/OAuth2Integration.csproj b/test/WebSites/OAuth2Integration/OAuth2Integration.csproj
index 6213a123d7..ce5ecf0a4e 100644
--- a/test/WebSites/OAuth2Integration/OAuth2Integration.csproj
+++ b/test/WebSites/OAuth2Integration/OAuth2Integration.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -14,4 +14,10 @@
     <ProjectReference Include="..\..\..\src\Swashbuckle.AspNetCore.SwaggerGen\Swashbuckle.AspNetCore.SwaggerGen.csproj" />
     <ProjectReference Include="..\..\..\src\Swashbuckle.AspNetCore.SwaggerUI\Swashbuckle.AspNetCore.SwaggerUI.csproj" />
   </ItemGroup>
+
+  <!-- This is just a sample for testing - updating to Duende.IdentityServer can be done at some point in the future -->
+  <ItemGroup>
+    <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-55p7-v223-x366" />
+    <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-ff4q-64jc-gx98" />
+  </ItemGroup>
 </Project>
diff --git a/test/WebSites/ReDoc/ReDoc.csproj b/test/WebSites/ReDoc/ReDoc.csproj
index a12405310d..f4ee71b5e9 100644
--- a/test/WebSites/ReDoc/ReDoc.csproj
+++ b/test/WebSites/ReDoc/ReDoc.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/TestFirst.IntegrationTests/TestFirst.IntegrationTests.csproj b/test/WebSites/TestFirst.IntegrationTests/TestFirst.IntegrationTests.csproj
index 62dfbcccd3..4b35ce21d0 100644
--- a/test/WebSites/TestFirst.IntegrationTests/TestFirst.IntegrationTests.csproj
+++ b/test/WebSites/TestFirst.IntegrationTests/TestFirst.IntegrationTests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/TestFirst/TestFirst.csproj b/test/WebSites/TestFirst/TestFirst.csproj
index ef0580e64e..43420665f9 100644
--- a/test/WebSites/TestFirst/TestFirst.csproj
+++ b/test/WebSites/TestFirst/TestFirst.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/WebSites/TopLevelSwaggerDoc/TopLevelSwaggerDoc.csproj b/test/WebSites/TopLevelSwaggerDoc/TopLevelSwaggerDoc.csproj
index 9c90a9ad79..1f904c96db 100644
--- a/test/WebSites/TopLevelSwaggerDoc/TopLevelSwaggerDoc.csproj
+++ b/test/WebSites/TopLevelSwaggerDoc/TopLevelSwaggerDoc.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
diff --git a/test/WebSites/WebApi.Aot/WebApi.Aot.csproj b/test/WebSites/WebApi.Aot/WebApi.Aot.csproj
index f264d1d349..3f87b1ee29 100644
--- a/test/WebSites/WebApi.Aot/WebApi.Aot.csproj
+++ b/test/WebSites/WebApi.Aot/WebApi.Aot.csproj
@@ -5,7 +5,7 @@
     <InvariantGlobalization>true</InvariantGlobalization>
     <Nullable>enable</Nullable>
     <PublishAot>true</PublishAot>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <TrimmerSingleWarn>false</TrimmerSingleWarn>
   </PropertyGroup>
 
diff --git a/test/WebSites/WebApi/WebApi.csproj b/test/WebSites/WebApi/WebApi.csproj
index be737b6c89..1d6b038443 100644
--- a/test/WebSites/WebApi/WebApi.csproj
+++ b/test/WebSites/WebApi/WebApi.csproj
@@ -4,7 +4,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <RootNamespace>WebApi</RootNamespace>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
   </PropertyGroup>