diff --git a/src/ProjectTemplates/Web.ProjectTemplates/BlazorServerWeb-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/BlazorServerWeb-CSharp.csproj.in
index fb2add30603f..844e9fb3a0f7 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/BlazorServerWeb-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/BlazorServerWeb-CSharp.csproj.in
@@ -7,6 +7,7 @@
     <WebProject_DirectoryAccessLevelKey Condition="'$(OrganizationalAuth)' == 'True' AND '$(OrgReadAccess)' == 'True'">1</WebProject_DirectoryAccessLevelKey>
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">BlazorServerWeb_CSharp</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <!--#if (IndividualLocalAuth && !UseLocalDB) -->
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Client.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Client.csproj.in
index 4fbe364042a7..0d2a155b6059 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Client.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Client.csproj.in
@@ -8,6 +8,7 @@
     <!--#if Hosted -->
     <AssemblyName Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">`$(AssemblyName.Replace(' ', '_'))</AssemblyName>
     <!--#endif -->
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Server.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Server.csproj.in
index 67f34756c0fc..203f86cc4ec7 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Server.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Server.csproj.in
@@ -8,6 +8,7 @@
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">ComponentsWebAssembly-CSharp.Server</RootNamespace>
     <AssemblyName Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">`$(AssemblyName.Replace(' ', '_'))</AssemblyName>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Shared.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Shared.csproj.in
index fdffee5bc537..90c3c887d6e1 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Shared.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/ComponentsWebAssembly-CSharp.Shared.csproj.in
@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>${DefaultNetCoreTargetFramework}</TargetFramework>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/EmptyWeb-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/EmptyWeb-CSharp.csproj.in
index f685d2d72dac..bcda65f31ff9 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/EmptyWeb-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/EmptyWeb-CSharp.csproj.in
@@ -4,6 +4,7 @@
     <TargetFramework>${DefaultNetCoreTargetFramework}</TargetFramework>
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.WebApplication1</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
 </Project>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/GrpcService-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/GrpcService-CSharp.csproj.in
index f7a69fba22f2..57df6d556e24 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/GrpcService-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/GrpcService-CSharp.csproj.in
@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>${DefaultNetCoreTargetFramework}</TargetFramework>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/RazorClassLibrary-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/RazorClassLibrary-CSharp.csproj.in
index 298bcecd8dd1..b3dd68132f3d 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/RazorClassLibrary-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/RazorClassLibrary-CSharp.csproj.in
@@ -4,6 +4,7 @@
     <TargetFramework>${DefaultNetCoreTargetFramework}</TargetFramework>
     <AddRazorSupportForMvc Condition="'$(SupportPagesAndViews)' == 'True'">true</AddRazorSupportForMvc>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.RazorClassLibrary1</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup Condition="'$(SupportPagesAndViews)' == 'True'">
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/RazorPagesWeb-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/RazorPagesWeb-CSharp.csproj.in
index 5869c4f86890..879ba26464b0 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/RazorPagesWeb-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/RazorPagesWeb-CSharp.csproj.in
@@ -6,6 +6,7 @@
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.WebApplication1</RootNamespace>
     <CopyRefAssembliesToPublishDirectory Condition="'$(RazorRuntimeCompilation)'=='true'">false</CopyRefAssembliesToPublishDirectory>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
   <!--#if (IndividualLocalAuth && !UseLocalDB) -->
 
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/StarterWeb-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/StarterWeb-CSharp.csproj.in
index 2da0a7fcb7d4..e43660dfef73 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/StarterWeb-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/StarterWeb-CSharp.csproj.in
@@ -6,6 +6,7 @@
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.WebApplication1</RootNamespace>
     <CopyRefAssembliesToPublishDirectory Condition="'$(RazorRuntimeCompilation)'=='true'">false</CopyRefAssembliesToPublishDirectory>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
   <!--#if (IndividualLocalAuth && !UseLocalDB) -->
 
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/WebApi-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/WebApi-CSharp.csproj.in
index 24f92d2299c7..e5f82d9fa7ce 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/WebApi-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/WebApi-CSharp.csproj.in
@@ -5,6 +5,7 @@
     <UserSecretsId Condition="'$(IndividualAuth)' == 'True' OR '$(OrganizationalAuth)' == 'True'">aspnet-Company.WebApplication1-53bc9b9d-9d6a-45d4-8429-2a2761773502</UserSecretsId>
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.WebApplication1</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
   <!--#if (OrganizationalAuth || IndividualB2CAuth || EnableOpenAPI) -->
 
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/Worker-CSharp.csproj.in b/src/ProjectTemplates/Web.ProjectTemplates/Worker-CSharp.csproj.in
index 284920b4f68c..689eb3667654 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/Worker-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.ProjectTemplates/Worker-CSharp.csproj.in
@@ -5,6 +5,7 @@
     <UserSecretsId>dotnet-Company.Application1-53bc9b9d-9d6a-45d4-8429-2a2761773502</UserSecretsId>
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.Application1</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/dotnetcli.host.json
index 3a5e6c90a856..1719350d8a57 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/dotnetcli.host.json
@@ -79,6 +79,10 @@
     "CallsMicrosoftGraph": {
         "longName": "calls-graph",
         "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/template.json
index 3d052b0b98e2..d0a371fdec2d 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/.template.config/template.json
@@ -438,6 +438,12 @@
       "datatype": "bool",
       "description": "If specified, skips the automatic restore of the project on create.",
       "defaultValue": "false"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Areas/Identity/Pages/Shared/_LoginPartial.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Areas/Identity/Pages/Shared/_LoginPartial.cshtml
index a4f854aac31f..eda27e908a71 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Areas/Identity/Pages/Shared/_LoginPartial.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Areas/Identity/Pages/Shared/_LoginPartial.cshtml
@@ -7,7 +7,7 @@
 @if (SignInManager.IsSignedIn(User))
 {
     <li class="nav-item">
-        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity.Name!</a>
+        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity?.Name!</a>
     </li>
     <li class="nav-item">
         <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="/" method="post">
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Data/WeatherForecast.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Data/WeatherForecast.cs
index dbe0d36a71e1..230c10abeef7 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Data/WeatherForecast.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Data/WeatherForecast.cs
@@ -10,6 +10,10 @@ public class WeatherForecast
 
         public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
 
+#if (!Nullable)
         public string Summary { get; set; }
+#else
+        public string? Summary { get; set; }
+#endif
     }
 }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml
index 6b3b6a193041..00df0904e9cf 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml
@@ -18,7 +18,7 @@
             <h1 class="text-danger">Error.</h1>
             <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-            @if (Model.ShowRequestId)
+            @if (Model?.ShowRequestId ?? false)
             {
                 <p>
                     <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml.cs
index 4c944dc5d82c..affc4f466500 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorServerWeb-CSharp/Pages/Error.cshtml.cs
@@ -13,7 +13,11 @@ namespace BlazorServerWeb_CSharp.Pages
     [IgnoreAntiforgeryToken]
     public class ErrorModel : PageModel
     {
+#if (!Nullable)
         public string RequestId { get; set; }
+#else
+        public string? RequestId { get; set; }
+#endif
 
         public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
 
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/dotnetcli.host.json
index f4f07149c87a..7cc5a0ac71f5 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/dotnetcli.host.json
@@ -89,6 +89,10 @@
     "CallsMicrosoftGraph": {
         "longName": "calls-graph",
         "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   }
 }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/template.json
index 4fba7cc9b54f..7f6bc8acd0ae 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/template.json
@@ -483,6 +483,12 @@
     "GenerateApiOrGraph": {
         "type": "computed",
         "value": "(GenerateApi || GenerateGraph)"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "tags": {
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Client/Pages/FetchData.razor b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Client/Pages/FetchData.razor
index a36d7d157d4b..ecc068bab0ad 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Client/Pages/FetchData.razor
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Client/Pages/FetchData.razor
@@ -74,7 +74,11 @@ else
 
         public int TemperatureC { get; set; }
 
+@*#if (!Nullable)
         public string Summary { get; set; }
+#else
+        public string? Summary { get; set; }
+#endif*@
 
         public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
     }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Areas/Identity/Pages/Shared/_LoginPartial.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Areas/Identity/Pages/Shared/_LoginPartial.cshtml
index 913f4c479bf7..1be0a5451871 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Areas/Identity/Pages/Shared/_LoginPartial.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Areas/Identity/Pages/Shared/_LoginPartial.cshtml
@@ -15,7 +15,7 @@
 @if (SignInManager.IsSignedIn(User))
 {
     <li class="nav-item">
-        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity.Name!</a>
+        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity?.Name!</a>
     </li>
     <li class="nav-item">
         <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="/" method="post">
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml
index b1ff51af394a..08b78a568f93 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml
@@ -18,7 +18,7 @@
             <h1 class="text-danger">Error.</h1>
             <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-            @if (Model.ShowRequestId)
+            @if (Model?.ShowRequestId ?? false)
             {
                 <p>
                     <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml.cs
index 92282ce4c268..9d95b405e0d8 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Server/Pages/Error.cshtml.cs
@@ -13,7 +13,11 @@ namespace ComponentsWebAssembly_CSharp.Server.Pages
     [IgnoreAntiforgeryToken]
     public class ErrorModel : PageModel
     {
+#if (!Nullable)
         public string RequestId { get; set; }
+#else
+        public string? RequestId { get; set; }
+#endif
 
         public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
 
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Shared/WeatherForecast.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Shared/WeatherForecast.cs
index 32e3d002de0b..3b44eebd1737 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Shared/WeatherForecast.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/Shared/WeatherForecast.cs
@@ -10,7 +10,11 @@ public class WeatherForecast
 
         public int TemperatureC { get; set; }
 
+#if (!Nullable)
         public string Summary { get; set; }
+#else
+        public string? Summary { get; set; }
+#endif
 
         public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
     }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/dotnetcli.host.json
index 79c2dc39e3ab..c7c2081085d1 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/dotnetcli.host.json
@@ -21,6 +21,10 @@
     "NoHttps": {
       "longName": "no-https",
       "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/template.json
index a2bfac90afa5..672432b859aa 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/template.json
@@ -112,6 +112,12 @@
       "datatype": "bool",
       "defaultValue": "false",
       "description": "Whether to turn off HTTPS. This option only applies if Individual, IndividualB2C, SingleOrg, or MultiOrg aren't used for --auth."
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/dotnetcli.host.json
index 51aa5b982eb5..65962282fbeb 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/dotnetcli.host.json
@@ -8,6 +8,10 @@
     "ExcludeLaunchSettings": {
       "longName": "exclude-launch-settings",
       "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/template.json
index 89185ed294e4..8a2812293518 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/template.json
@@ -58,6 +58,12 @@
       "datatype": "bool",
       "description": "If specified, skips the automatic restore of the project on create.",
       "defaultValue": "false"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/dotnetcli.host.json
index c658c087dd54..fc311e744e45 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/dotnetcli.host.json
@@ -12,6 +12,10 @@
     "SupportPagesAndViews": {
       "longName": "support-pages-and-views",
       "shortName": "s"
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   }
 }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/template.json
index 3ef9e65cff98..2190ef076f08 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/.template.config/template.json
@@ -69,6 +69,12 @@
       "datatype": "bool",
       "defaultValue": "false",
       "description": "Whether to support adding traditional Razor pages and Views in addition to components to this library."
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/dotnetcli.host.json
index a5b697ebcdb7..6b84694f93e1 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/dotnetcli.host.json
@@ -83,6 +83,10 @@
     "CallsMicrosoftGraph": {
         "longName": "calls-graph",
         "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/template.json
index e43dfecf46ec..0a950b0d1633 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/template.json
@@ -368,6 +368,12 @@
     "GenerateApiOrGraph": {
         "type": "computed",
         "value": "(GenerateApi || GenerateGraph)"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml
index 6f92b9565570..975f5be4d77c 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml
@@ -7,7 +7,7 @@
 <h1 class="text-danger">Error.</h1>
 <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-@if (Model.ShowRequestId)
+@if (Model?.ShowRequestId ?? false)
 {
     <p>
         <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml.cs
index 10108d2b1017..3867334f3bca 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Error.cshtml.cs
@@ -13,7 +13,11 @@ namespace Company.WebApplication1.Pages
     [IgnoreAntiforgeryToken]
     public class ErrorModel : PageModel
     {
+#if (!Nullable)
         public string RequestId { get; set; }
+#else
+        public string? RequestId { get; set; }
+#endif
 
         public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
 
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.Identity.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.Identity.cshtml
index c45b365fd466..7cc3147e0816 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.Identity.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.Identity.cshtml
@@ -6,7 +6,7 @@
 @if (SignInManager.IsSignedIn(User))
 {
     <li class="nav-item">
-        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity.Name!</a>
+        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity?.Name!</a>
     </li>
     <li class="nav-item">
         <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Page("/", new { area = "" })" method="post" >
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.OrgAuth.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.OrgAuth.cshtml
index 8f7c9041e83e..bae914eb1ba0 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.OrgAuth.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/Pages/Shared/_LoginPartial.OrgAuth.cshtml
@@ -11,7 +11,7 @@
 
 <ul class="navbar-nav">
 @*#if (IndividualB2CAuth)
-@if (User.Identity.IsAuthenticated)
+@if (User.Identity?.IsAuthenticated == true)
 {
         @if (!string.IsNullOrEmpty(options.EditProfilePolicyId))
         {
@@ -38,7 +38,7 @@ else
         </li>
 }
 #else
-@if (User.Identity.IsAuthenticated)
+@if (User.Identity?.IsAuthenticated == true)
 {
         <li class="nav-item">
             <span class="navbar-text text-dark">Hello @User.Identity.Name!</span>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/dotnetcli.host.json
index 07d2cda7491d..d6688e4cbc10 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/dotnetcli.host.json
@@ -83,6 +83,10 @@
     "CallsMicrosoftGraph": {
         "longName": "calls-graph",
         "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/template.json
index 6616642912c1..339dfc9e8b00 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/template.json
@@ -364,6 +364,12 @@
     "GenerateApiOrGraph": {
         "type": "computed",
         "value": "(GenerateApi || GenerateGraph)"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Models/ErrorViewModel.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Models/ErrorViewModel.cs
index 6fe06d375908..5be6c9cef170 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Models/ErrorViewModel.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Models/ErrorViewModel.cs
@@ -4,7 +4,11 @@ namespace Company.WebApplication1.Models
 {
     public class ErrorViewModel
     {
+#if (!Nullable)
         public string RequestId { get; set; }
+#else
+        public string? RequestId { get; set; }
+#endif
 
         public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
     }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/Error.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/Error.cshtml
index a1e04783c67a..e8dd22190c6e 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/Error.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/Error.cshtml
@@ -6,7 +6,7 @@
 <h1 class="text-danger">Error.</h1>
 <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-@if (Model.ShowRequestId)
+@if (Model?.ShowRequestId ?? false)
 {
     <p>
         <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.Identity.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.Identity.cshtml
index cd256aa9249f..921dbe1ebc8b 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.Identity.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.Identity.cshtml
@@ -6,7 +6,7 @@
 @if (SignInManager.IsSignedIn(User))
 {
     <li class="nav-item">
-        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity.Name!</a>
+        <a  class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity?.Name!</a>
     </li>
     <li class="nav-item">
         <form  class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Action("Index", "Home", new { area = "" })">
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.OrgAuth.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.OrgAuth.cshtml
index da2cbaf70188..fe8076391e56 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.OrgAuth.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/Views/Shared/_LoginPartial.OrgAuth.cshtml
@@ -12,7 +12,7 @@ var options = AzureADB2COptions.Value;
 
 <ul class="navbar-nav">
 @*#if (IndividualB2CAuth)
-@if (User.Identity.IsAuthenticated)
+@if (User.Identity?.IsAuthenticated == true)
 {
         @if (!string.IsNullOrEmpty(options.EditProfilePolicyId))
         {
@@ -39,7 +39,7 @@ else
         </li>
 }
 #else
-@if (User.Identity.IsAuthenticated)
+@if (User.Identity?.IsAuthenticated == true)
 {
         <li class="nav-item">
             <span class="navbar-text text-dark">Hello @User.Identity.Name!</span>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-FSharp/Views/Shared/Error.cshtml b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-FSharp/Views/Shared/Error.cshtml
index 06c02f4a3841..1f79c59a1191 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-FSharp/Views/Shared/Error.cshtml
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-FSharp/Views/Shared/Error.cshtml
@@ -1,4 +1,4 @@
-@using Company.WebApplication1.Models 
+@using Company.WebApplication1.Models
 @model ErrorViewModel
 @{
     ViewData["Title"] = "Error";
@@ -7,7 +7,7 @@
 <h1 class="text-danger">Error.</h1>
 <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-@if (Model.ShowRequestId)
+@if (Model?.ShowRequestId ?? false)
 {
     <p>
         <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/dotnetcli.host.json
index b16a1f9a27a1..04ce069e1788 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/dotnetcli.host.json
@@ -35,7 +35,7 @@
     "DefaultScope": {
       "longName": "default-scope",
       "shortName": ""
-    },    
+    },
     "Framework": {
       "longName": "framework"
     },
@@ -75,9 +75,13 @@
     "DisableOpenAPI": {
       "longName": "no-openapi",
       "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
     ""
   ]
-}
\ No newline at end of file
+}
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/template.json
index 1e31e0b5363d..260531941765 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/template.json
@@ -277,6 +277,12 @@
     "EnableOpenAPI": {
       "type": "computed",
       "value": "(!DisableOpenAPI)"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/WeatherForecast.cs b/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/WeatherForecast.cs
index 128b3473696e..01b870efbe48 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/WeatherForecast.cs
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/WeatherForecast.cs
@@ -10,6 +10,10 @@ public class WeatherForecast
 
         public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
 
+#if (!Nullable)
         public string Summary { get; set; }
+#else
+        public string? Summary { get; set; }
+#endif
     }
 }
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/dotnetcli.host.json
index b1cf98e39bb8..3f088f276a3c 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/dotnetcli.host.json
@@ -11,6 +11,10 @@
     "ExcludeLaunchSettings": {
       "longName": "exclude-launch-settings",
       "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/template.json
index 19358bf86a30..b1a3a95cd70e 100644
--- a/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.ProjectTemplates/content/Worker-CSharp/.template.config/template.json
@@ -67,6 +67,12 @@
       "datatype": "bool",
       "description": "If specified, skips the automatic restore of the project on create.",
       "defaultValue": "false"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "primaryOutputs": [
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/Angular-CSharp.csproj.in b/src/ProjectTemplates/Web.Spa.ProjectTemplates/Angular-CSharp.csproj.in
index bd68bc27bc01..aae44e395d26 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/Angular-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/Angular-CSharp.csproj.in
@@ -9,6 +9,7 @@
     <SpaProxyLaunchCommand>npm start</SpaProxyLaunchCommand>
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.WebApplication1</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/React-CSharp.csproj.in b/src/ProjectTemplates/Web.Spa.ProjectTemplates/React-CSharp.csproj.in
index 43706ed0b473..d4b404253736 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/React-CSharp.csproj.in
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/React-CSharp.csproj.in
@@ -13,6 +13,7 @@
     <SpaProxyLaunchCommand>npm start</SpaProxyLaunchCommand>
     <NoDefaultLaunchSettingsFile Condition="'$(ExcludeLaunchSettings)' == 'True'">True</NoDefaultLaunchSettingsFile>
     <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">Company.WebApplication1</RootNamespace>
+    <Nullable Condition="'$(Nullable)' == 'true'">enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/dotnetcli.host.json
index 1a247d9d6282..0ff4e391bb9a 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/dotnetcli.host.json
@@ -27,6 +27,10 @@
     "NoHttps": {
       "longName": "no-https",
       "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/template.json
index 1302b3fd2ae5..f7332c9e5f74 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/.template.config/template.json
@@ -193,6 +193,12 @@
     "HostIdentifier": {
       "type": "bind",
       "binding": "HostIdentifier"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "tags": {
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml
index 6f92b9565570..975f5be4d77c 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml
@@ -7,7 +7,7 @@
 <h1 class="text-danger">Error.</h1>
 <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-@if (Model.ShowRequestId)
+@if (Model?.ShowRequestId ?? false)
 {
     <p>
         <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml.cs b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml.cs
index b31bc6addd1f..ecf2761e95db 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml.cs
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Error.cshtml.cs
@@ -19,7 +19,11 @@ public ErrorModel(ILogger<ErrorModel> logger)
             _logger = logger;
         }
 
+#if (!Nullable)
         public string RequestId { get; set; }
+#else
+        public string? RequestId { get; set; }
+#endif
 
         public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
 
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Shared/_LoginPartial.cshtml b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Shared/_LoginPartial.cshtml
index f2884db7adca..8e7fccb5b361 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Shared/_LoginPartial.cshtml
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/Pages/Shared/_LoginPartial.cshtml
@@ -16,7 +16,7 @@
     @if (SignInManager.IsSignedIn(User))
     {
         <li class="nav-item">
-            <a class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity.Name!</a>
+            <a class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity?.Name!</a>
         </li>
         <li class="nav-item">
             <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="/">
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/WeatherForecast.cs b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/WeatherForecast.cs
index 128b3473696e..01b870efbe48 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/WeatherForecast.cs
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/Angular-CSharp/WeatherForecast.cs
@@ -10,6 +10,10 @@ public class WeatherForecast
 
         public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
 
+#if (!Nullable)
         public string Summary { get; set; }
+#else
+        public string? Summary { get; set; }
+#endif
     }
 }
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/dotnetcli.host.json b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/dotnetcli.host.json
index 1a247d9d6282..0ff4e391bb9a 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/dotnetcli.host.json
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/dotnetcli.host.json
@@ -27,6 +27,10 @@
     "NoHttps": {
       "longName": "no-https",
       "shortName": ""
+    },
+    "Nullable": {
+      "longName": "nullable",
+      "shortName": ""
     }
   },
   "usageExamples": [
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/template.json b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/template.json
index 0d47ffbc17d5..2d892bbe9fc0 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/template.json
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/.template.config/template.json
@@ -195,6 +195,12 @@
     "HostIdentifier": {
       "type": "bind",
       "binding": "HostIdentifier"
+    },
+    "Nullable": {
+      "type": "parameter",
+      "datatype": "bool",
+      "defaultValue": "true",
+      "description": "Whether to enable nullable reference types for this project."
     }
   },
   "tags": {
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml
index 6f92b9565570..975f5be4d77c 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml
@@ -7,7 +7,7 @@
 <h1 class="text-danger">Error.</h1>
 <h2 class="text-danger">An error occurred while processing your request.</h2>
 
-@if (Model.ShowRequestId)
+@if (Model?.ShowRequestId ?? false)
 {
     <p>
         <strong>Request ID:</strong> <code>@Model.RequestId</code>
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml.cs b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml.cs
index b31bc6addd1f..ecf2761e95db 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml.cs
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Error.cshtml.cs
@@ -19,7 +19,11 @@ public ErrorModel(ILogger<ErrorModel> logger)
             _logger = logger;
         }
 
+#if (!Nullable)
         public string RequestId { get; set; }
+#else
+        public string? RequestId { get; set; }
+#endif
 
         public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
 
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Shared/_LoginPartial.cshtml b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Shared/_LoginPartial.cshtml
index f2884db7adca..8e7fccb5b361 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Shared/_LoginPartial.cshtml
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/Pages/Shared/_LoginPartial.cshtml
@@ -16,7 +16,7 @@
     @if (SignInManager.IsSignedIn(User))
     {
         <li class="nav-item">
-            <a class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity.Name!</a>
+            <a class="nav-link text-dark" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @User.Identity?.Name!</a>
         </li>
         <li class="nav-item">
             <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="/">
diff --git a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/WeatherForecast.cs b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/WeatherForecast.cs
index 128b3473696e..01b870efbe48 100644
--- a/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/WeatherForecast.cs
+++ b/src/ProjectTemplates/Web.Spa.ProjectTemplates/content/React-CSharp/WeatherForecast.cs
@@ -10,6 +10,10 @@ public class WeatherForecast
 
         public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
 
+#if (!Nullable)
         public string Summary { get; set; }
+#else
+        public string? Summary { get; set; }
+#endif
     }
 }