diff --git a/src/Hosting/TestHost/src/ClientHandler.cs b/src/Hosting/TestHost/src/ClientHandler.cs
index bb3d98105a9f..299b84bea6bd 100644
--- a/src/Hosting/TestHost/src/ClientHandler.cs
+++ b/src/Hosting/TestHost/src/ClientHandler.cs
@@ -184,7 +184,7 @@ protected override async Task<HttpResponseMessage> SendAsync(
             // Copy trailers to the response message when the response stream is complete
             contextBuilder.RegisterResponseReadCompleteCallback(context =>
             {
-                var responseTrailersFeature = context.Features.Get<IHttpResponseTrailersFeature>();
+                var responseTrailersFeature = context.Features.Get<IHttpResponseTrailersFeature>()!;
 
                 foreach (var trailer in responseTrailersFeature.Trailers)
                 {
@@ -196,7 +196,7 @@ protected override async Task<HttpResponseMessage> SendAsync(
             var httpContext = await contextBuilder.SendAsync(cancellationToken);
 
             response.StatusCode = (HttpStatusCode)httpContext.Response.StatusCode;
-            response.ReasonPhrase = httpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase;
+            response.ReasonPhrase = httpContext.Features.Get<IHttpResponseFeature>()!.ReasonPhrase;
             response.RequestMessage = request;
             response.Version = request.Version;
 
diff --git a/src/Hosting/TestHost/src/HttpContextBuilder.cs b/src/Hosting/TestHost/src/HttpContextBuilder.cs
index 8fb74385c1a7..ef9b6e5faee3 100644
--- a/src/Hosting/TestHost/src/HttpContextBuilder.cs
+++ b/src/Hosting/TestHost/src/HttpContextBuilder.cs
@@ -225,7 +225,7 @@ internal async Task ReturnResponseMessageAsync()
                 {
                     newFeatures[pair.Key] = pair.Value;
                 }
-                var serverResponseFeature = _httpContext.Features.Get<IHttpResponseFeature>();
+                var serverResponseFeature = _httpContext.Features.Get<IHttpResponseFeature>()!;
                 // The client gets a deep copy of this so they can interact with the body stream independently of the server.
                 var clientResponseFeature = new HttpResponseFeature()
                 {
diff --git a/src/Http/Http.Extensions/src/ResponseExtensions.cs b/src/Http/Http.Extensions/src/ResponseExtensions.cs
index 5fe1614be4a2..46bb247944c3 100644
--- a/src/Http/Http.Extensions/src/ResponseExtensions.cs
+++ b/src/Http/Http.Extensions/src/ResponseExtensions.cs
@@ -16,7 +16,7 @@ public static void Clear(this HttpResponse response)
                 throw new InvalidOperationException("The response cannot be cleared, it has already started sending.");
             }
             response.StatusCode = 200;
-            response.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = null;
+            response.HttpContext.Features.Get<IHttpResponseFeature>()!.ReasonPhrase = null;
             response.Headers.Clear();
             if (response.Body.CanSeek)
             {
diff --git a/src/Http/Http.Extensions/src/SendFileResponseExtensions.cs b/src/Http/Http.Extensions/src/SendFileResponseExtensions.cs
index a9fd30908b9a..a888c096112d 100644
--- a/src/Http/Http.Extensions/src/SendFileResponseExtensions.cs
+++ b/src/Http/Http.Extensions/src/SendFileResponseExtensions.cs
@@ -143,7 +143,7 @@ private static async Task SendFileAsyncCore(HttpResponse response, string fileNa
         {
             var useRequestAborted = !cancellationToken.CanBeCanceled;
             var localCancel = useRequestAborted ? response.HttpContext.RequestAborted : cancellationToken;
-            var sendFile = response.HttpContext.Features.Get<IHttpResponseBodyFeature>();
+            var sendFile = response.HttpContext.Features.Get<IHttpResponseBodyFeature>()!;
 
             try
             {
diff --git a/src/Http/Http.Features/src/FeatureCollection.cs b/src/Http/Http.Features/src/FeatureCollection.cs
index d46a1e38e5bd..626277ee134f 100644
--- a/src/Http/Http.Features/src/FeatureCollection.cs
+++ b/src/Http/Http.Features/src/FeatureCollection.cs
@@ -98,7 +98,7 @@ public IEnumerator<KeyValuePair<Type, object>> GetEnumerator()
             return (TFeature?)this[typeof(TFeature)];
         }
 
-        public void Set<TFeature>(TFeature instance)
+        public void Set<TFeature>(TFeature? instance)
         {
             this[typeof(TFeature)] = instance;
         }
diff --git a/src/Http/Http.Features/src/IFeatureCollection.cs b/src/Http/Http.Features/src/IFeatureCollection.cs
index 6d087df337d7..ff1f3ec69676 100644
--- a/src/Http/Http.Features/src/IFeatureCollection.cs
+++ b/src/Http/Http.Features/src/IFeatureCollection.cs
@@ -33,13 +33,13 @@ public interface IFeatureCollection : IEnumerable<KeyValuePair<Type, object>>
         /// </summary>
         /// <typeparam name="TFeature">The feature key.</typeparam>
         /// <returns>The requested feature, or null if it is not present.</returns>
-        TFeature Get<TFeature>();
+        TFeature? Get<TFeature>();
 
         /// <summary>
         /// Sets the given feature in the collection.
         /// </summary>
         /// <typeparam name="TFeature">The feature key.</typeparam>
         /// <param name="instance">The feature value.</param>
-        void Set<TFeature>(TFeature instance);
+        void Set<TFeature>(TFeature? instance);
     }
 }
diff --git a/src/Http/Http.Features/src/PublicAPI.Shipped.txt b/src/Http/Http.Features/src/PublicAPI.Shipped.txt
index 6c0b614457a9..18866d4bcb71 100644
--- a/src/Http/Http.Features/src/PublicAPI.Shipped.txt
+++ b/src/Http/Http.Features/src/PublicAPI.Shipped.txt
@@ -26,7 +26,7 @@ Microsoft.AspNetCore.Http.Features.FeatureCollection.FeatureCollection(Microsoft
 Microsoft.AspNetCore.Http.Features.FeatureCollection.Get<TFeature>() -> TFeature?
 Microsoft.AspNetCore.Http.Features.FeatureCollection.GetEnumerator() -> System.Collections.Generic.IEnumerator<System.Collections.Generic.KeyValuePair<System.Type!, object!>>!
 Microsoft.AspNetCore.Http.Features.FeatureCollection.IsReadOnly.get -> bool
-Microsoft.AspNetCore.Http.Features.FeatureCollection.Set<TFeature>(TFeature instance) -> void
+Microsoft.AspNetCore.Http.Features.FeatureCollection.Set<TFeature>(TFeature? instance) -> void
 Microsoft.AspNetCore.Http.Features.FeatureCollection.this[System.Type! key].get -> object?
 Microsoft.AspNetCore.Http.Features.FeatureCollection.this[System.Type! key].set -> void
 Microsoft.AspNetCore.Http.Features.FeatureReference<T>
@@ -46,10 +46,10 @@ Microsoft.AspNetCore.Http.Features.HttpsCompressionMode.Compress = 2 -> Microsof
 Microsoft.AspNetCore.Http.Features.HttpsCompressionMode.Default = 0 -> Microsoft.AspNetCore.Http.Features.HttpsCompressionMode
 Microsoft.AspNetCore.Http.Features.HttpsCompressionMode.DoNotCompress = 1 -> Microsoft.AspNetCore.Http.Features.HttpsCompressionMode
 Microsoft.AspNetCore.Http.Features.IFeatureCollection
-Microsoft.AspNetCore.Http.Features.IFeatureCollection.Get<TFeature>() -> TFeature
+Microsoft.AspNetCore.Http.Features.IFeatureCollection.Get<TFeature>() -> TFeature?
 Microsoft.AspNetCore.Http.Features.IFeatureCollection.IsReadOnly.get -> bool
 Microsoft.AspNetCore.Http.Features.IFeatureCollection.Revision.get -> int
-Microsoft.AspNetCore.Http.Features.IFeatureCollection.Set<TFeature>(TFeature instance) -> void
+Microsoft.AspNetCore.Http.Features.IFeatureCollection.Set<TFeature>(TFeature? instance) -> void
 Microsoft.AspNetCore.Http.Features.IFeatureCollection.this[System.Type! key].get -> object?
 Microsoft.AspNetCore.Http.Features.IFeatureCollection.this[System.Type! key].set -> void
 Microsoft.AspNetCore.Http.Features.IFormFeature
diff --git a/src/Http/Http/src/Internal/DefaultHttpResponse.cs b/src/Http/Http/src/Internal/DefaultHttpResponse.cs
index 6caa939444ee..554616bd7536 100644
--- a/src/Http/Http/src/Internal/DefaultHttpResponse.cs
+++ b/src/Http/Http/src/Internal/DefaultHttpResponse.cs
@@ -69,7 +69,7 @@ public override Stream Body
             get { return HttpResponseBodyFeature.Stream; }
             set
             {
-                var otherFeature = _features.Collection.Get<IHttpResponseBodyFeature>();
+                var otherFeature = _features.Collection.Get<IHttpResponseBodyFeature>()!;
 
                 if (otherFeature is StreamResponseBodyFeature streamFeature
                     && streamFeature.PriorFeature != null
diff --git a/src/Http/Http/src/Internal/ResponseCookies.cs b/src/Http/Http/src/Internal/ResponseCookies.cs
index e6e582bfda0b..4a34b055d604 100644
--- a/src/Http/Http/src/Internal/ResponseCookies.cs
+++ b/src/Http/Http/src/Internal/ResponseCookies.cs
@@ -28,7 +28,7 @@ internal class ResponseCookies : IResponseCookies
         internal ResponseCookies(IFeatureCollection features)
         {
             _features = features;
-            Headers = _features.Get<IHttpResponseFeature>().Headers;
+            Headers = _features.Get<IHttpResponseFeature>()!.Headers;
         }
 
         private IHeaderDictionary Headers { get; set; }
diff --git a/src/Middleware/ResponseCompression/src/ResponseCompressionMiddleware.cs b/src/Middleware/ResponseCompression/src/ResponseCompressionMiddleware.cs
index 0d0715db213a..e37b39dde7d2 100644
--- a/src/Middleware/ResponseCompression/src/ResponseCompressionMiddleware.cs
+++ b/src/Middleware/ResponseCompression/src/ResponseCompressionMiddleware.cs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
@@ -54,6 +55,8 @@ public async Task Invoke(HttpContext context)
             var originalBodyFeature = context.Features.Get<IHttpResponseBodyFeature>();
             var originalCompressionFeature = context.Features.Get<IHttpsCompressionFeature>();
 
+            Debug.Assert(originalBodyFeature != null);
+
             var compressionBody = new ResponseCompressionBody(context, _provider, originalBodyFeature);
             context.Features.Set<IHttpResponseBodyFeature>(compressionBody);
             context.Features.Set<IHttpsCompressionFeature>(compressionBody);
diff --git a/src/Middleware/Rewrite/src/UrlActions/CustomResponseAction.cs b/src/Middleware/Rewrite/src/UrlActions/CustomResponseAction.cs
index ecd63fd32d6c..23fdfba6c105 100644
--- a/src/Middleware/Rewrite/src/UrlActions/CustomResponseAction.cs
+++ b/src/Middleware/Rewrite/src/UrlActions/CustomResponseAction.cs
@@ -26,7 +26,7 @@ public override void ApplyAction(RewriteContext context, BackReferenceCollection
 
             if (!string.IsNullOrEmpty(StatusReason))
             {
-                context.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = StatusReason;
+                context.HttpContext.Features.Get<IHttpResponseFeature>()!.ReasonPhrase = StatusReason;
             }
 
             if (!string.IsNullOrEmpty(StatusDescription))
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs
index bc37696cb529..d8ad519873de 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs
@@ -12,6 +12,8 @@
 using Microsoft.Net.Http.Headers;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
     internal enum KnownHeaderType
@@ -6712,7 +6714,7 @@ protected override bool CopyToFast(KeyValuePair<string, StringValues>[] array, i
                     array[arrayIndex] = new KeyValuePair<string, StringValues>(HeaderNames.ContentLength, HeaderUtilities.FormatNonNegativeInt64(_contentLength.Value));
                     ++arrayIndex;
                 }
-            ((ICollection<KeyValuePair<string, StringValues>>)MaybeUnknown)?.CopyTo(array, arrayIndex);
+            ((ICollection<KeyValuePair<string, StringValues>>?)MaybeUnknown)?.CopyTo(array, arrayIndex);
 
             return true;
         }
@@ -12724,7 +12726,7 @@ protected override bool CopyToFast(KeyValuePair<string, StringValues>[] array, i
                     array[arrayIndex] = new KeyValuePair<string, StringValues>(HeaderNames.ContentLength, HeaderUtilities.FormatNonNegativeInt64(_contentLength.Value));
                     ++arrayIndex;
                 }
-            ((ICollection<KeyValuePair<string, StringValues>>)MaybeUnknown)?.CopyTo(array, arrayIndex);
+            ((ICollection<KeyValuePair<string, StringValues>>?)MaybeUnknown)?.CopyTo(array, arrayIndex);
 
             return true;
         }
@@ -12816,7 +12818,7 @@ internal unsafe void CopyToFast(ref BufferWriter<PipeWriter> output)
                         {
                             tempBits ^= 0x8000000000000000L;
                             output.Write(HeaderBytes.Slice(640, 18));
-                            output.WriteNumeric((ulong)ContentLength.Value);
+                            output.WriteNumeric((ulong)ContentLength.GetValueOrDefault());
                             if (tempBits == 0)
                             {
                                 return;
@@ -13266,10 +13268,10 @@ private struct HeaderReferences
             public StringValues _AccessControlExposeHeaders;
             public StringValues _AccessControlMaxAge;
             
-            public byte[] _rawConnection;
-            public byte[] _rawDate;
-            public byte[] _rawTransferEncoding;
-            public byte[] _rawServer;
+            public byte[]? _rawConnection;
+            public byte[]? _rawDate;
+            public byte[]? _rawTransferEncoding;
+            public byte[]? _rawServer;
         }
 
         public partial struct Enumerator
@@ -14149,7 +14151,7 @@ protected override bool CopyToFast(KeyValuePair<string, StringValues>[] array, i
                     array[arrayIndex] = new KeyValuePair<string, StringValues>(HeaderNames.ContentLength, HeaderUtilities.FormatNonNegativeInt64(_contentLength.Value));
                     ++arrayIndex;
                 }
-            ((ICollection<KeyValuePair<string, StringValues>>)MaybeUnknown)?.CopyTo(array, arrayIndex);
+            ((ICollection<KeyValuePair<string, StringValues>>?)MaybeUnknown)?.CopyTo(array, arrayIndex);
 
             return true;
         }
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.Generated.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.Generated.cs
index 52c0308f89a1..f6420cc0c955 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.Generated.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.Generated.cs
@@ -9,42 +9,44 @@
 using Microsoft.AspNetCore.Http.Features.Authentication;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Features;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
     internal partial class HttpProtocol : IFeatureCollection
     {
-        private object _currentIHttpRequestFeature;
-        private object _currentIHttpRequestBodyDetectionFeature;
-        private object _currentIHttpResponseFeature;
-        private object _currentIHttpResponseBodyFeature;
-        private object _currentIRequestBodyPipeFeature;
-        private object _currentIHttpRequestIdentifierFeature;
-        private object _currentIServiceProvidersFeature;
-        private object _currentIHttpRequestLifetimeFeature;
-        private object _currentIHttpConnectionFeature;
-        private object _currentIRouteValuesFeature;
-        private object _currentIEndpointFeature;
-        private object _currentIHttpAuthenticationFeature;
-        private object _currentIHttpRequestTrailersFeature;
-        private object _currentIQueryFeature;
-        private object _currentIFormFeature;
-        private object _currentIHttpUpgradeFeature;
-        private object _currentIHttp2StreamIdFeature;
-        private object _currentIHttpResponseTrailersFeature;
-        private object _currentIResponseCookiesFeature;
-        private object _currentIItemsFeature;
-        private object _currentITlsConnectionFeature;
-        private object _currentIHttpWebSocketFeature;
-        private object _currentISessionFeature;
-        private object _currentIHttpMaxRequestBodySizeFeature;
-        private object _currentIHttpMinRequestBodyDataRateFeature;
-        private object _currentIHttpMinResponseDataRateFeature;
-        private object _currentIHttpBodyControlFeature;
-        private object _currentIHttpResetFeature;
+        private object? _currentIHttpRequestFeature;
+        private object? _currentIHttpRequestBodyDetectionFeature;
+        private object? _currentIHttpResponseFeature;
+        private object? _currentIHttpResponseBodyFeature;
+        private object? _currentIRequestBodyPipeFeature;
+        private object? _currentIHttpRequestIdentifierFeature;
+        private object? _currentIServiceProvidersFeature;
+        private object? _currentIHttpRequestLifetimeFeature;
+        private object? _currentIHttpConnectionFeature;
+        private object? _currentIRouteValuesFeature;
+        private object? _currentIEndpointFeature;
+        private object? _currentIHttpAuthenticationFeature;
+        private object? _currentIHttpRequestTrailersFeature;
+        private object? _currentIQueryFeature;
+        private object? _currentIFormFeature;
+        private object? _currentIHttpUpgradeFeature;
+        private object? _currentIHttp2StreamIdFeature;
+        private object? _currentIHttpResponseTrailersFeature;
+        private object? _currentIResponseCookiesFeature;
+        private object? _currentIItemsFeature;
+        private object? _currentITlsConnectionFeature;
+        private object? _currentIHttpWebSocketFeature;
+        private object? _currentISessionFeature;
+        private object? _currentIHttpMaxRequestBodySizeFeature;
+        private object? _currentIHttpMinRequestBodyDataRateFeature;
+        private object? _currentIHttpMinResponseDataRateFeature;
+        private object? _currentIHttpBodyControlFeature;
+        private object? _currentIHttpResetFeature;
 
         private int _featureRevision;
 
-        private List<KeyValuePair<Type, object>> MaybeExtra;
+        private List<KeyValuePair<Type, object>>? MaybeExtra;
 
         private void FastReset()
         {
@@ -87,7 +89,7 @@ internal void ResetFeatureCollection()
             _featureRevision++;
         }
 
-        private object ExtraFeatureGet(Type key)
+        private object? ExtraFeatureGet(Type key)
         {
             if (MaybeExtra == null)
             {
@@ -104,33 +106,50 @@ private object ExtraFeatureGet(Type key)
             return null;
         }
 
-        private void ExtraFeatureSet(Type key, object value)
+        private void ExtraFeatureSet(Type key, object? value)
         {
-            if (MaybeExtra == null)
+            if (value == null)
             {
-                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                if (MaybeExtra == null)
+                {
+                    return;
+                }
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {
+                    if (MaybeExtra[i].Key == key)
+                    {
+                        MaybeExtra.RemoveAt(i);
+                        return;
+                    }
+                }
             }
-
-            for (var i = 0; i < MaybeExtra.Count; i++)
+            else
             {
-                if (MaybeExtra[i].Key == key)
+                if (MaybeExtra == null)
                 {
-                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
-                    return;
+                    MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                }
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {
+                    if (MaybeExtra[i].Key == key)
+                    {
+                        MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
+                        return;
+                    }
                 }
+                MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
             }
-            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
         }
 
         bool IFeatureCollection.IsReadOnly => false;
 
         int IFeatureCollection.Revision => _featureRevision;
 
-        object IFeatureCollection.this[Type key]
+        object? IFeatureCollection.this[Type key]
         {
             get
             {
-                object feature = null;
+                object? feature = null;
                 if (key == typeof(IHttpRequestFeature))
                 {
                     feature = _currentIHttpRequestFeature;
@@ -374,124 +393,124 @@ object IFeatureCollection.this[Type key]
             }
         }
 
-        TFeature IFeatureCollection.Get<TFeature>()
+        TFeature? IFeatureCollection.Get<TFeature>() where TFeature : default
         {
-            TFeature feature = default;
+            TFeature? feature = default;
             if (typeof(TFeature) == typeof(IHttpRequestFeature))
             {
-                feature = (TFeature)_currentIHttpRequestFeature;
+                feature = (TFeature?)_currentIHttpRequestFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpRequestBodyDetectionFeature))
             {
-                feature = (TFeature)_currentIHttpRequestBodyDetectionFeature;
+                feature = (TFeature?)_currentIHttpRequestBodyDetectionFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpResponseFeature))
             {
-                feature = (TFeature)_currentIHttpResponseFeature;
+                feature = (TFeature?)_currentIHttpResponseFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpResponseBodyFeature))
             {
-                feature = (TFeature)_currentIHttpResponseBodyFeature;
+                feature = (TFeature?)_currentIHttpResponseBodyFeature;
             }
             else if (typeof(TFeature) == typeof(IRequestBodyPipeFeature))
             {
-                feature = (TFeature)_currentIRequestBodyPipeFeature;
+                feature = (TFeature?)_currentIRequestBodyPipeFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpRequestIdentifierFeature))
             {
-                feature = (TFeature)_currentIHttpRequestIdentifierFeature;
+                feature = (TFeature?)_currentIHttpRequestIdentifierFeature;
             }
             else if (typeof(TFeature) == typeof(IServiceProvidersFeature))
             {
-                feature = (TFeature)_currentIServiceProvidersFeature;
+                feature = (TFeature?)_currentIServiceProvidersFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpRequestLifetimeFeature))
             {
-                feature = (TFeature)_currentIHttpRequestLifetimeFeature;
+                feature = (TFeature?)_currentIHttpRequestLifetimeFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpConnectionFeature))
             {
-                feature = (TFeature)_currentIHttpConnectionFeature;
+                feature = (TFeature?)_currentIHttpConnectionFeature;
             }
             else if (typeof(TFeature) == typeof(IRouteValuesFeature))
             {
-                feature = (TFeature)_currentIRouteValuesFeature;
+                feature = (TFeature?)_currentIRouteValuesFeature;
             }
             else if (typeof(TFeature) == typeof(IEndpointFeature))
             {
-                feature = (TFeature)_currentIEndpointFeature;
+                feature = (TFeature?)_currentIEndpointFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpAuthenticationFeature))
             {
-                feature = (TFeature)_currentIHttpAuthenticationFeature;
+                feature = (TFeature?)_currentIHttpAuthenticationFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpRequestTrailersFeature))
             {
-                feature = (TFeature)_currentIHttpRequestTrailersFeature;
+                feature = (TFeature?)_currentIHttpRequestTrailersFeature;
             }
             else if (typeof(TFeature) == typeof(IQueryFeature))
             {
-                feature = (TFeature)_currentIQueryFeature;
+                feature = (TFeature?)_currentIQueryFeature;
             }
             else if (typeof(TFeature) == typeof(IFormFeature))
             {
-                feature = (TFeature)_currentIFormFeature;
+                feature = (TFeature?)_currentIFormFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpUpgradeFeature))
             {
-                feature = (TFeature)_currentIHttpUpgradeFeature;
+                feature = (TFeature?)_currentIHttpUpgradeFeature;
             }
             else if (typeof(TFeature) == typeof(IHttp2StreamIdFeature))
             {
-                feature = (TFeature)_currentIHttp2StreamIdFeature;
+                feature = (TFeature?)_currentIHttp2StreamIdFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpResponseTrailersFeature))
             {
-                feature = (TFeature)_currentIHttpResponseTrailersFeature;
+                feature = (TFeature?)_currentIHttpResponseTrailersFeature;
             }
             else if (typeof(TFeature) == typeof(IResponseCookiesFeature))
             {
-                feature = (TFeature)_currentIResponseCookiesFeature;
+                feature = (TFeature?)_currentIResponseCookiesFeature;
             }
             else if (typeof(TFeature) == typeof(IItemsFeature))
             {
-                feature = (TFeature)_currentIItemsFeature;
+                feature = (TFeature?)_currentIItemsFeature;
             }
             else if (typeof(TFeature) == typeof(ITlsConnectionFeature))
             {
-                feature = (TFeature)_currentITlsConnectionFeature;
+                feature = (TFeature?)_currentITlsConnectionFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpWebSocketFeature))
             {
-                feature = (TFeature)_currentIHttpWebSocketFeature;
+                feature = (TFeature?)_currentIHttpWebSocketFeature;
             }
             else if (typeof(TFeature) == typeof(ISessionFeature))
             {
-                feature = (TFeature)_currentISessionFeature;
+                feature = (TFeature?)_currentISessionFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpMaxRequestBodySizeFeature))
             {
-                feature = (TFeature)_currentIHttpMaxRequestBodySizeFeature;
+                feature = (TFeature?)_currentIHttpMaxRequestBodySizeFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpMinRequestBodyDataRateFeature))
             {
-                feature = (TFeature)_currentIHttpMinRequestBodyDataRateFeature;
+                feature = (TFeature?)_currentIHttpMinRequestBodyDataRateFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpMinResponseDataRateFeature))
             {
-                feature = (TFeature)_currentIHttpMinResponseDataRateFeature;
+                feature = (TFeature?)_currentIHttpMinResponseDataRateFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpBodyControlFeature))
             {
-                feature = (TFeature)_currentIHttpBodyControlFeature;
+                feature = (TFeature?)_currentIHttpBodyControlFeature;
             }
             else if (typeof(TFeature) == typeof(IHttpResetFeature))
             {
-                feature = (TFeature)_currentIHttpResetFeature;
+                feature = (TFeature?)_currentIHttpResetFeature;
             }
             else if (MaybeExtra != null)
             {
-                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
+                feature = (TFeature?)(ExtraFeatureGet(typeof(TFeature)));
             }
 
             if (feature == null)
@@ -502,7 +521,7 @@ TFeature IFeatureCollection.Get<TFeature>()
             return feature;
         }
 
-        void IFeatureCollection.Set<TFeature>(TFeature feature)
+        void IFeatureCollection.Set<TFeature>(TFeature? feature) where TFeature : default
         {
             _featureRevision++;
             if (typeof(TFeature) == typeof(IHttpRequestFeature))
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs
index 41254f837d40..05e017cbfea1 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs
@@ -96,7 +96,7 @@ private void AppendContentLength(ReadOnlySpan<byte> value)
         }
 
         [MethodImpl(MethodImplOptions.NoInlining)]
-        private void AppendContentLengthCustomEncoding(ReadOnlySpan<byte> value, Encoding customEncoding)
+        private void AppendContentLengthCustomEncoding(ReadOnlySpan<byte> value, Encoding? customEncoding)
         {
             if (_contentLength.HasValue)
             {
@@ -105,7 +105,7 @@ private void AppendContentLengthCustomEncoding(ReadOnlySpan<byte> value, Encodin
 
             // long.MaxValue = 9223372036854775807 (19 chars)
             Span<char> decodedChars = stackalloc char[20];
-            var numChars = customEncoding.GetChars(value, decodedChars);
+            var numChars = customEncoding!.GetChars(value, decodedChars);
             long parsed = -1;
 
             if (numChars > 19 ||
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.Generated.cs b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.Generated.cs
index 290fea38f5ab..fb271a155cdd 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.Generated.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.Generated.cs
@@ -3,6 +3,8 @@
 
 using System;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2
 {
     internal partial class Http2Connection
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Connection.cs b/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Connection.cs
index fb8a6d9adef3..f640c274c14a 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Connection.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Connection.cs
@@ -210,6 +210,7 @@ internal async Task InnerProcessRequestsAsync<TContext>(IHttpApplication<TContex
                     var streamIdFeature = streamContext.Features.Get<IStreamIdFeature>();
 
                     Debug.Assert(quicStreamFeature != null);
+                    Debug.Assert(streamIdFeature != null);
 
                     var httpConnectionContext = new Http3StreamContext(
                         streamContext.ConnectionId,
diff --git a/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Stream.cs b/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Stream.cs
index 51f570acaa7a..46b3d6d9a942 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Stream.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http3/Http3Stream.cs
@@ -62,8 +62,8 @@ public Http3Stream(Http3Connection http3Connection, Http3StreamContext context)
             _http3Connection = http3Connection;
             _context = context;
 
-            _errorCodeFeature = _context.ConnectionFeatures.Get<IProtocolErrorCodeFeature>();
-            _streamIdFeature = _context.ConnectionFeatures.Get<IStreamIdFeature>();
+            _errorCodeFeature = _context.ConnectionFeatures.Get<IProtocolErrorCodeFeature>()!;
+            _streamIdFeature = _context.ConnectionFeatures.Get<IStreamIdFeature>()!;
 
             _frameWriter = new Http3FrameWriter(
                 context.Transport.Output,
diff --git a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.Generated.cs b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.Generated.cs
index 89443f3de0f2..684efdb0f227 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.Generated.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Infrastructure/HttpUtilities.Generated.cs
@@ -6,6 +6,8 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 {
     internal static partial class HttpUtilities
diff --git a/src/Servers/Kestrel/Core/test/Http1HttpProtocolFeatureCollectionTests.cs b/src/Servers/Kestrel/Core/test/Http1HttpProtocolFeatureCollectionTests.cs
index d71a5865de2b..d7d15d61250f 100644
--- a/src/Servers/Kestrel/Core/test/Http1HttpProtocolFeatureCollectionTests.cs
+++ b/src/Servers/Kestrel/Core/test/Http1HttpProtocolFeatureCollectionTests.cs
@@ -159,6 +159,19 @@ public void Http1HasIHttpMinResponseDataRateFeature()
             Assert.NotNull(_collection.Get<IHttpMinResponseDataRateFeature>());
         }
 
+        [Fact]
+        public void SetExtraFeatureAsNull()
+        {
+            _collection[typeof(string)] = null;
+            Assert.Equal(0, _collection.Count(kv => kv.Key == typeof(string)));
+
+            _collection[typeof(string)] = "A string";
+            Assert.Equal(1, _collection.Count(kv => kv.Key == typeof(string)));
+
+            _collection[typeof(string)] = null;
+            Assert.Equal(0, _collection.Count(kv => kv.Key == typeof(string)));
+        }
+
         private void CompareGenericGetterToIndexer()
         {
             Assert.Same(_collection.Get<IHttpRequestFeature>(), _collection[typeof(IHttpRequestFeature)]);
diff --git a/src/Servers/Kestrel/Transport.Quic/src/Internal/QuicConnectionContext.cs b/src/Servers/Kestrel/Transport.Quic/src/Internal/QuicConnectionContext.cs
index 21da83c29c90..07b23d6c0969 100644
--- a/src/Servers/Kestrel/Transport.Quic/src/Internal/QuicConnectionContext.cs
+++ b/src/Servers/Kestrel/Transport.Quic/src/Internal/QuicConnectionContext.cs
@@ -96,7 +96,7 @@ public override ValueTask<ConnectionContext> ConnectAsync(IFeatureCollection? fe
 
             if (features != null)
             {
-                var streamDirectionFeature = features.Get<IStreamDirectionFeature>();
+                var streamDirectionFeature = features.Get<IStreamDirectionFeature>()!;
                 if (streamDirectionFeature.CanRead)
                 {
                     quicStream = _connection.OpenBidirectionalStream();
diff --git a/src/Servers/Kestrel/shared/KnownHeaders.cs b/src/Servers/Kestrel/shared/KnownHeaders.cs
index 16d65a833d1a..e6541998aa29 100644
--- a/src/Servers/Kestrel/shared/KnownHeaders.cs
+++ b/src/Servers/Kestrel/shared/KnownHeaders.cs
@@ -723,6 +723,8 @@ public static string GeneratedFile()
 using Microsoft.Net.Http.Headers;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {{
     internal enum KnownHeaderType
@@ -1026,7 +1028,7 @@ protected override bool CopyToFast(KeyValuePair<string, StringValues>[] array, i
                     array[arrayIndex] = new KeyValuePair<string, StringValues>(HeaderNames.ContentLength, HeaderUtilities.FormatNonNegativeInt64(_contentLength.Value));
                     ++arrayIndex;
                 }}
-            ((ICollection<KeyValuePair<string, StringValues>>)MaybeUnknown)?.CopyTo(array, arrayIndex);
+            ((ICollection<KeyValuePair<string, StringValues>>?)MaybeUnknown)?.CopyTo(array, arrayIndex);
 
             return true;
         }}
@@ -1070,7 +1072,7 @@ internal unsafe void CopyToFast(ref BufferWriter<PipeWriter> output)
                                 break; // OutputHeader
                             }}")}" : $@"
                             output.Write(HeaderBytes.Slice({hi.Header.BytesOffset}, {hi.Header.BytesCount}));
-                            output.WriteNumeric((ulong)ContentLength.Value);
+                            output.WriteNumeric((ulong)ContentLength.GetValueOrDefault());
                             if (tempBits == 0)
                             {{
                                 return;
@@ -1148,7 +1150,7 @@ private struct HeaderReferences
         {{{Each(loop.Headers.Where(header => header.Identifier != "ContentLength"), header => @"
             public StringValues _" + header.Identifier + ";")}
             {Each(loop.Headers.Where(header => header.EnhancedSetter), header => @"
-            public byte[] _raw" + header.Identifier + ";")}
+            public byte[]? _raw" + header.Identifier + ";")}
         }}
 
         public partial struct Enumerator
diff --git a/src/Servers/Kestrel/shared/TransportConnection.Generated.cs b/src/Servers/Kestrel/shared/TransportConnection.Generated.cs
index a9ba1cd76284..b35954bb6fa2 100644
--- a/src/Servers/Kestrel/shared/TransportConnection.Generated.cs
+++ b/src/Servers/Kestrel/shared/TransportConnection.Generated.cs
@@ -8,19 +8,21 @@
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.Http.Features;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Connections
 {
     internal partial class TransportConnection : IFeatureCollection
     {
-        private object _currentIConnectionIdFeature;
-        private object _currentIConnectionTransportFeature;
-        private object _currentIConnectionItemsFeature;
-        private object _currentIMemoryPoolFeature;
-        private object _currentIConnectionLifetimeFeature;
+        private object? _currentIConnectionIdFeature;
+        private object? _currentIConnectionTransportFeature;
+        private object? _currentIConnectionItemsFeature;
+        private object? _currentIMemoryPoolFeature;
+        private object? _currentIConnectionLifetimeFeature;
 
         private int _featureRevision;
 
-        private List<KeyValuePair<Type, object>> MaybeExtra;
+        private List<KeyValuePair<Type, object>>? MaybeExtra;
 
         private void FastReset()
         {
@@ -40,7 +42,7 @@ internal void ResetFeatureCollection()
             _featureRevision++;
         }
 
-        private object ExtraFeatureGet(Type key)
+        private object? ExtraFeatureGet(Type key)
         {
             if (MaybeExtra == null)
             {
@@ -57,33 +59,50 @@ private object ExtraFeatureGet(Type key)
             return null;
         }
 
-        private void ExtraFeatureSet(Type key, object value)
+        private void ExtraFeatureSet(Type key, object? value)
         {
-            if (MaybeExtra == null)
+            if (value == null)
             {
-                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                if (MaybeExtra == null)
+                {
+                    return;
+                }
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {
+                    if (MaybeExtra[i].Key == key)
+                    {
+                        MaybeExtra.RemoveAt(i);
+                        return;
+                    }
+                }
             }
-
-            for (var i = 0; i < MaybeExtra.Count; i++)
+            else
             {
-                if (MaybeExtra[i].Key == key)
+                if (MaybeExtra == null)
                 {
-                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
-                    return;
+                    MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                }
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {
+                    if (MaybeExtra[i].Key == key)
+                    {
+                        MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
+                        return;
+                    }
                 }
+                MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
             }
-            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
         }
 
         bool IFeatureCollection.IsReadOnly => false;
 
         int IFeatureCollection.Revision => _featureRevision;
 
-        object IFeatureCollection.this[Type key]
+        object? IFeatureCollection.this[Type key]
         {
             get
             {
-                object feature = null;
+                object? feature = null;
                 if (key == typeof(IConnectionIdFeature))
                 {
                     feature = _currentIConnectionIdFeature;
@@ -143,38 +162,38 @@ object IFeatureCollection.this[Type key]
             }
         }
 
-        TFeature IFeatureCollection.Get<TFeature>()
+        TFeature? IFeatureCollection.Get<TFeature>() where TFeature : default
         {
-            TFeature feature = default;
+            TFeature? feature = default;
             if (typeof(TFeature) == typeof(IConnectionIdFeature))
             {
-                feature = (TFeature)_currentIConnectionIdFeature;
+                feature = (TFeature?)_currentIConnectionIdFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionTransportFeature))
             {
-                feature = (TFeature)_currentIConnectionTransportFeature;
+                feature = (TFeature?)_currentIConnectionTransportFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionItemsFeature))
             {
-                feature = (TFeature)_currentIConnectionItemsFeature;
+                feature = (TFeature?)_currentIConnectionItemsFeature;
             }
             else if (typeof(TFeature) == typeof(IMemoryPoolFeature))
             {
-                feature = (TFeature)_currentIMemoryPoolFeature;
+                feature = (TFeature?)_currentIMemoryPoolFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionLifetimeFeature))
             {
-                feature = (TFeature)_currentIConnectionLifetimeFeature;
+                feature = (TFeature?)_currentIConnectionLifetimeFeature;
             }
             else if (MaybeExtra != null)
             {
-                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
+                feature = (TFeature?)(ExtraFeatureGet(typeof(TFeature)));
             }
 
             return feature;
         }
 
-        void IFeatureCollection.Set<TFeature>(TFeature feature)
+        void IFeatureCollection.Set<TFeature>(TFeature? feature) where TFeature : default
         {
             _featureRevision++;
             if (typeof(TFeature) == typeof(IConnectionIdFeature))
diff --git a/src/Servers/Kestrel/shared/TransportMultiplexedConnection.Generated.cs b/src/Servers/Kestrel/shared/TransportMultiplexedConnection.Generated.cs
index e7df1de198e7..cdfc0bff16c3 100644
--- a/src/Servers/Kestrel/shared/TransportMultiplexedConnection.Generated.cs
+++ b/src/Servers/Kestrel/shared/TransportMultiplexedConnection.Generated.cs
@@ -8,19 +8,21 @@
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.Http.Features;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Connections
 {
     internal partial class TransportMultiplexedConnection : IFeatureCollection
     {
-        private object _currentIConnectionIdFeature;
-        private object _currentIConnectionTransportFeature;
-        private object _currentIConnectionItemsFeature;
-        private object _currentIMemoryPoolFeature;
-        private object _currentIConnectionLifetimeFeature;
+        private object? _currentIConnectionIdFeature;
+        private object? _currentIConnectionTransportFeature;
+        private object? _currentIConnectionItemsFeature;
+        private object? _currentIMemoryPoolFeature;
+        private object? _currentIConnectionLifetimeFeature;
 
         private int _featureRevision;
 
-        private List<KeyValuePair<Type, object>> MaybeExtra;
+        private List<KeyValuePair<Type, object>>? MaybeExtra;
 
         private void FastReset()
         {
@@ -40,7 +42,7 @@ internal void ResetFeatureCollection()
             _featureRevision++;
         }
 
-        private object ExtraFeatureGet(Type key)
+        private object? ExtraFeatureGet(Type key)
         {
             if (MaybeExtra == null)
             {
@@ -57,33 +59,50 @@ private object ExtraFeatureGet(Type key)
             return null;
         }
 
-        private void ExtraFeatureSet(Type key, object value)
+        private void ExtraFeatureSet(Type key, object? value)
         {
-            if (MaybeExtra == null)
+            if (value == null)
             {
-                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                if (MaybeExtra == null)
+                {
+                    return;
+                }
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {
+                    if (MaybeExtra[i].Key == key)
+                    {
+                        MaybeExtra.RemoveAt(i);
+                        return;
+                    }
+                }
             }
-
-            for (var i = 0; i < MaybeExtra.Count; i++)
+            else
             {
-                if (MaybeExtra[i].Key == key)
+                if (MaybeExtra == null)
                 {
-                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
-                    return;
+                    MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                }
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {
+                    if (MaybeExtra[i].Key == key)
+                    {
+                        MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
+                        return;
+                    }
                 }
+                MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
             }
-            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
         }
 
         bool IFeatureCollection.IsReadOnly => false;
 
         int IFeatureCollection.Revision => _featureRevision;
 
-        object IFeatureCollection.this[Type key]
+        object? IFeatureCollection.this[Type key]
         {
             get
             {
-                object feature = null;
+                object? feature = null;
                 if (key == typeof(IConnectionIdFeature))
                 {
                     feature = _currentIConnectionIdFeature;
@@ -143,38 +162,38 @@ object IFeatureCollection.this[Type key]
             }
         }
 
-        TFeature IFeatureCollection.Get<TFeature>()
+        TFeature? IFeatureCollection.Get<TFeature>() where TFeature : default
         {
-            TFeature feature = default;
+            TFeature? feature = default;
             if (typeof(TFeature) == typeof(IConnectionIdFeature))
             {
-                feature = (TFeature)_currentIConnectionIdFeature;
+                feature = (TFeature?)_currentIConnectionIdFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionTransportFeature))
             {
-                feature = (TFeature)_currentIConnectionTransportFeature;
+                feature = (TFeature?)_currentIConnectionTransportFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionItemsFeature))
             {
-                feature = (TFeature)_currentIConnectionItemsFeature;
+                feature = (TFeature?)_currentIConnectionItemsFeature;
             }
             else if (typeof(TFeature) == typeof(IMemoryPoolFeature))
             {
-                feature = (TFeature)_currentIMemoryPoolFeature;
+                feature = (TFeature?)_currentIMemoryPoolFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionLifetimeFeature))
             {
-                feature = (TFeature)_currentIConnectionLifetimeFeature;
+                feature = (TFeature?)_currentIConnectionLifetimeFeature;
             }
             else if (MaybeExtra != null)
             {
-                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
+                feature = (TFeature?)(ExtraFeatureGet(typeof(TFeature)));
             }
 
             return feature;
         }
 
-        void IFeatureCollection.Set<TFeature>(TFeature feature)
+        void IFeatureCollection.Set<TFeature>(TFeature? feature) where TFeature : default
         {
             _featureRevision++;
             if (typeof(TFeature) == typeof(IConnectionIdFeature))
diff --git a/src/Servers/Kestrel/tools/CodeGenerator/FeatureCollectionGenerator.cs b/src/Servers/Kestrel/tools/CodeGenerator/FeatureCollectionGenerator.cs
index 0e91c137d4e7..3f75cd4e21e6 100644
--- a/src/Servers/Kestrel/tools/CodeGenerator/FeatureCollectionGenerator.cs
+++ b/src/Servers/Kestrel/tools/CodeGenerator/FeatureCollectionGenerator.cs
@@ -27,15 +27,17 @@ public static string GenerateFile(string namespaceName, string className, string
 using System.Collections.Generic;
 {extraUsings}
 
+#nullable enable
+
 namespace {namespaceName}
 {{
     internal partial class {className} : IFeatureCollection
     {{{Each(features, feature => $@"
-        private object _current{feature.Name};")}
+        private object? _current{feature.Name};")}
 
         private int _featureRevision;
 
-        private List<KeyValuePair<Type, object>> MaybeExtra;
+        private List<KeyValuePair<Type, object>>? MaybeExtra;
 
         private void FastReset()
         {{{Each(implementedFeatures, feature => $@"
@@ -52,7 +54,7 @@ internal void ResetFeatureCollection()
             _featureRevision++;
         }}
 
-        private object ExtraFeatureGet(Type key)
+        private object? ExtraFeatureGet(Type key)
         {{
             if (MaybeExtra == null)
             {{
@@ -69,33 +71,50 @@ private object ExtraFeatureGet(Type key)
             return null;
         }}
 
-        private void ExtraFeatureSet(Type key, object value)
+        private void ExtraFeatureSet(Type key, object? value)
         {{
-            if (MaybeExtra == null)
+            if (value == null)
             {{
-                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                if (MaybeExtra == null)
+                {{
+                    return;
+                }}
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {{
+                    if (MaybeExtra[i].Key == key)
+                    {{
+                        MaybeExtra.RemoveAt(i);
+                        return;
+                    }}
+                }}
             }}
-
-            for (var i = 0; i < MaybeExtra.Count; i++)
+            else
             {{
-                if (MaybeExtra[i].Key == key)
+                if (MaybeExtra == null)
                 {{
-                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
-                    return;
+                    MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+                }}
+                for (var i = 0; i < MaybeExtra.Count; i++)
+                {{
+                    if (MaybeExtra[i].Key == key)
+                    {{
+                        MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
+                        return;
+                    }}
                 }}
+                MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
             }}
-            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
         }}
 
         bool IFeatureCollection.IsReadOnly => false;
 
         int IFeatureCollection.Revision => _featureRevision;
 
-        object IFeatureCollection.this[Type key]
+        object? IFeatureCollection.this[Type key]
         {{
             get
             {{
-                object feature = null;{Each(features, feature => $@"
+                object? feature = null;{Each(features, feature => $@"
                 {(feature.Index != 0 ? "else " : "")}if (key == typeof({feature.Name}))
                 {{
                     feature = _current{feature.Name};
@@ -123,16 +142,16 @@ object IFeatureCollection.this[Type key]
             }}
         }}
 
-        TFeature IFeatureCollection.Get<TFeature>()
+        TFeature? IFeatureCollection.Get<TFeature>() where TFeature : default
         {{
-            TFeature feature = default;{Each(features, feature => $@"
+            TFeature? feature = default;{Each(features, feature => $@"
             {(feature.Index != 0 ? "else " : "")}if (typeof(TFeature) == typeof({feature.Name}))
             {{
-                feature = (TFeature)_current{feature.Name};
+                feature = (TFeature?)_current{feature.Name};
             }}")}
             else if (MaybeExtra != null)
             {{
-                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
+                feature = (TFeature?)(ExtraFeatureGet(typeof(TFeature)));
             }}{(string.IsNullOrEmpty(fallbackFeatures) ? "" : $@"
 
             if (feature == null)
@@ -143,7 +162,7 @@ TFeature IFeatureCollection.Get<TFeature>()
             return feature;
         }}
 
-        void IFeatureCollection.Set<TFeature>(TFeature feature)
+        void IFeatureCollection.Set<TFeature>(TFeature? feature) where TFeature : default
         {{
             _featureRevision++;{Each(features, feature => $@"
             {(feature.Index != 0 ? "else " : "")}if (typeof(TFeature) == typeof({feature.Name}))
diff --git a/src/Servers/Kestrel/tools/CodeGenerator/HttpUtilities/HttpUtilities.cs b/src/Servers/Kestrel/tools/CodeGenerator/HttpUtilities/HttpUtilities.cs
index 4edf81c09377..bb07d8713e5d 100644
--- a/src/Servers/Kestrel/tools/CodeGenerator/HttpUtilities/HttpUtilities.cs
+++ b/src/Servers/Kestrel/tools/CodeGenerator/HttpUtilities/HttpUtilities.cs
@@ -68,6 +68,8 @@ private static string GenerateFile(Tuple<string, String>[] httpMethods)
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
 
+#nullable enable
+
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure
 {{
     internal static partial class HttpUtilities
diff --git a/src/Servers/Kestrel/tools/CodeGenerator/ReadOnlySpanStaticDataGenerator.cs b/src/Servers/Kestrel/tools/CodeGenerator/ReadOnlySpanStaticDataGenerator.cs
index 96be0757adc0..9360db249197 100644
--- a/src/Servers/Kestrel/tools/CodeGenerator/ReadOnlySpanStaticDataGenerator.cs
+++ b/src/Servers/Kestrel/tools/CodeGenerator/ReadOnlySpanStaticDataGenerator.cs
@@ -24,6 +24,8 @@ public static string GenerateFile(string namespaceName, string className, IEnume
 
 using System;
 
+#nullable enable
+
 namespace {namespaceName}
 {{
     internal partial class {className}
diff --git a/src/SignalR/common/Http.Connections/src/Internal/Transports/ServerSentEventsServerTransport.cs b/src/SignalR/common/Http.Connections/src/Internal/Transports/ServerSentEventsServerTransport.cs
index b9bc12dbae5f..ffda642fa44a 100644
--- a/src/SignalR/common/Http.Connections/src/Internal/Transports/ServerSentEventsServerTransport.cs
+++ b/src/SignalR/common/Http.Connections/src/Internal/Transports/ServerSentEventsServerTransport.cs
@@ -39,7 +39,7 @@ public async Task ProcessRequestAsync(HttpContext context, CancellationToken tok
             context.Response.Headers[HeaderNames.Pragma] = "no-cache";
 
             // Make sure we disable all response buffering for SSE
-            var bufferingFeature = context.Features.Get<IHttpResponseBodyFeature>();
+            var bufferingFeature = context.Features.Get<IHttpResponseBodyFeature>()!;
             bufferingFeature.DisableBuffering();
 
             context.Response.Headers[HeaderNames.ContentEncoding] = "identity";