diff --git a/src/Mvc/Mvc.Core/src/ApiExplorer/IApiRequestFormatMetadataProvider.cs b/src/Mvc/Mvc.Core/src/ApiExplorer/IApiRequestFormatMetadataProvider.cs
index cfb942053215..50e84006030d 100644
--- a/src/Mvc/Mvc.Core/src/ApiExplorer/IApiRequestFormatMetadataProvider.cs
+++ b/src/Mvc/Mvc.Core/src/ApiExplorer/IApiRequestFormatMetadataProvider.cs
@@ -25,6 +25,6 @@ public interface IApiRequestFormatMetadataProvider
     /// </param>
     /// <returns>Content types which are supported by the <see cref="Formatters.IInputFormatter"/>.</returns>
     IReadOnlyList<string>? GetSupportedContentTypes(
-        string contentType,
+        string? contentType,
         Type objectType);
 }
diff --git a/src/Mvc/Mvc.Core/src/ApiExplorer/IApiResponseTypeMetadataProvider.cs b/src/Mvc/Mvc.Core/src/ApiExplorer/IApiResponseTypeMetadataProvider.cs
index c2c05b1746cb..679dbd71cdaa 100644
--- a/src/Mvc/Mvc.Core/src/ApiExplorer/IApiResponseTypeMetadataProvider.cs
+++ b/src/Mvc/Mvc.Core/src/ApiExplorer/IApiResponseTypeMetadataProvider.cs
@@ -25,6 +25,6 @@ public interface IApiResponseTypeMetadataProvider
     /// </param>
     /// <returns>Content types which are supported by the <see cref="Formatters.IOutputFormatter"/>.</returns>
     IReadOnlyList<string>? GetSupportedContentTypes(
-        string contentType,
+        string? contentType,
         Type objectType);
 }
diff --git a/src/Mvc/Mvc.Core/src/Formatters/InputFormatter.cs b/src/Mvc/Mvc.Core/src/Formatters/InputFormatter.cs
index 2474e63ab177..47a6fa1b5b27 100644
--- a/src/Mvc/Mvc.Core/src/Formatters/InputFormatter.cs
+++ b/src/Mvc/Mvc.Core/src/Formatters/InputFormatter.cs
@@ -118,7 +118,7 @@ public virtual Task<InputFormatterResult> ReadAsync(InputFormatterContext contex
     public abstract Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context);
 
     /// <inheritdoc />
-    public virtual IReadOnlyList<string>? GetSupportedContentTypes(string contentType, Type objectType)
+    public virtual IReadOnlyList<string>? GetSupportedContentTypes(string? contentType, Type objectType)
     {
         if (SupportedMediaTypes.Count == 0)
         {
diff --git a/src/Mvc/Mvc.Core/src/Formatters/OutputFormatter.cs b/src/Mvc/Mvc.Core/src/Formatters/OutputFormatter.cs
index 362171af2b8c..f14215f6ec28 100644
--- a/src/Mvc/Mvc.Core/src/Formatters/OutputFormatter.cs
+++ b/src/Mvc/Mvc.Core/src/Formatters/OutputFormatter.cs
@@ -30,7 +30,7 @@ protected virtual bool CanWriteType(Type? type)
 
     /// <inheritdoc />
     public virtual IReadOnlyList<string>? GetSupportedContentTypes(
-        string contentType,
+        string? contentType,
         Type objectType)
     {
         if (SupportedMediaTypes.Count == 0)
diff --git a/src/Mvc/Mvc.Core/src/PublicAPI.Unshipped.txt b/src/Mvc/Mvc.Core/src/PublicAPI.Unshipped.txt
index 08c1f5142578..1cd6a2b5200c 100644
--- a/src/Mvc/Mvc.Core/src/PublicAPI.Unshipped.txt
+++ b/src/Mvc/Mvc.Core/src/PublicAPI.Unshipped.txt
@@ -1,8 +1,16 @@
 #nullable enable
+*REMOVED*Microsoft.AspNetCore.Mvc.ApiExplorer.IApiRequestFormatMetadataProvider.GetSupportedContentTypes(string! contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
+Microsoft.AspNetCore.Mvc.ApiExplorer.IApiRequestFormatMetadataProvider.GetSupportedContentTypes(string? contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
 Microsoft.AspNetCore.Mvc.ApiExplorer.IApiResponseMetadataProvider.Description.get -> string?
+*REMOVED*Microsoft.AspNetCore.Mvc.ApiExplorer.IApiResponseTypeMetadataProvider.GetSupportedContentTypes(string! contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
+Microsoft.AspNetCore.Mvc.ApiExplorer.IApiResponseTypeMetadataProvider.GetSupportedContentTypes(string? contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
 Microsoft.AspNetCore.Mvc.ProducesAttribute.Description.get -> string?
 Microsoft.AspNetCore.Mvc.ProducesAttribute.Description.set -> void
 Microsoft.AspNetCore.Mvc.ProducesDefaultResponseTypeAttribute.Description.get -> string?
 Microsoft.AspNetCore.Mvc.ProducesDefaultResponseTypeAttribute.Description.set -> void
 Microsoft.AspNetCore.Mvc.ProducesResponseTypeAttribute.Description.get -> string?
 Microsoft.AspNetCore.Mvc.ProducesResponseTypeAttribute.Description.set -> void
+*REMOVED*virtual Microsoft.AspNetCore.Mvc.Formatters.InputFormatter.GetSupportedContentTypes(string! contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
+virtual Microsoft.AspNetCore.Mvc.Formatters.InputFormatter.GetSupportedContentTypes(string? contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
+*REMOVED*virtual Microsoft.AspNetCore.Mvc.Formatters.OutputFormatter.GetSupportedContentTypes(string! contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
+virtual Microsoft.AspNetCore.Mvc.Formatters.OutputFormatter.GetSupportedContentTypes(string? contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?