diff --git a/src/Shared/runtime/Http2/Hpack/HPackDecodingException.cs b/src/Shared/runtime/Http2/Hpack/HPackDecodingException.cs
index b0225bb6f9a1..ed2859df5744 100644
--- a/src/Shared/runtime/Http2/Hpack/HPackDecodingException.cs
+++ b/src/Shared/runtime/Http2/Hpack/HPackDecodingException.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel;
 using System.Runtime.Serialization;
 
 namespace System.Net.Http.HPack
@@ -21,6 +22,8 @@ public HPackDecodingException(string message, Exception innerException) : base(m
         {
         }
 
+        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
+        [EditorBrowsable(EditorBrowsableState.Never)]
         public HPackDecodingException(SerializationInfo info, StreamingContext context) : base(info, context)
         {
         }
diff --git a/src/Shared/runtime/Http2/Hpack/HuffmanDecodingException.cs b/src/Shared/runtime/Http2/Hpack/HuffmanDecodingException.cs
index 287497b7ee11..b83ca6502e8c 100644
--- a/src/Shared/runtime/Http2/Hpack/HuffmanDecodingException.cs
+++ b/src/Shared/runtime/Http2/Hpack/HuffmanDecodingException.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel;
 using System.Runtime.Serialization;
 
 namespace System.Net.Http.HPack
@@ -18,16 +19,26 @@ public HuffmanDecodingException(string message)
         {
         }
 
+#if NET8_0_OR_GREATER
+        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
+#endif
         private HuffmanDecodingException(SerializationInfo info, StreamingContext context)
             : base(info, context)
         {
         }
 
+#if NET8_0_OR_GREATER
+        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
+#endif
         void ISerializable.GetObjectData(SerializationInfo serializationInfo, StreamingContext streamingContext)
         {
             base.GetObjectData(serializationInfo, streamingContext);
         }
 
+#if NET8_0_OR_GREATER
+        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
+        [EditorBrowsable(EditorBrowsableState.Never)]
+#endif
         public override void GetObjectData(SerializationInfo serializationInfo, StreamingContext streamingContext)
         {
             base.GetObjectData(serializationInfo, streamingContext);
diff --git a/src/Shared/runtime/Http3/QPack/QPackDecodingException.cs b/src/Shared/runtime/Http3/QPack/QPackDecodingException.cs
index 760403267f45..5de0efff935d 100644
--- a/src/Shared/runtime/Http3/QPack/QPackDecodingException.cs
+++ b/src/Shared/runtime/Http3/QPack/QPackDecodingException.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel;
 using System.Runtime.Serialization;
 
 namespace System.Net.Http.QPack
@@ -20,6 +21,9 @@ public QPackDecodingException(string message, Exception innerException) : base(m
         {
         }
 
+#if NET8_0_OR_GREATER
+        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
+#endif
         private QPackDecodingException(SerializationInfo info, StreamingContext context) : base(info, context)
         {
         }
diff --git a/src/Shared/runtime/Http3/QPack/QPackEncodingException.cs b/src/Shared/runtime/Http3/QPack/QPackEncodingException.cs
index 6b5647e18e2e..7e6eb6f1b792 100644
--- a/src/Shared/runtime/Http3/QPack/QPackEncodingException.cs
+++ b/src/Shared/runtime/Http3/QPack/QPackEncodingException.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel;
 using System.Runtime.Serialization;
 
 namespace System.Net.Http.QPack
@@ -17,6 +18,9 @@ public QPackEncodingException(string message, Exception innerException)
         {
         }
 
+#if NET8_0_OR_GREATER
+        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
+#endif
         private QPackEncodingException(SerializationInfo info, StreamingContext context) : base(info, context)
         {
         }