diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1.md
new file mode 100644
index 0000000000..d777b4f9a3
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1.md
@@ -0,0 +1,11 @@
+# API Difference 9.0-preview7 vs 9.0-rc1
+
+API listing follows standard diff formatting.
+Lines preceded by a '+' are additions and a '-' indicates removal.
+
+* [Microsoft.AspNetCore.Builder](9.0-rc1_Microsoft.AspNetCore.Builder.md)
+* [Microsoft.AspNetCore.Components](9.0-rc1_Microsoft.AspNetCore.Components.md)
+* [Microsoft.AspNetCore.Components.Routing](9.0-rc1_Microsoft.AspNetCore.Components.Routing.md)
+* [Microsoft.AspNetCore.Components.Web.Virtualization](9.0-rc1_Microsoft.AspNetCore.Components.Web.Virtualization.md)
+* [Microsoft.AspNetCore.Http](9.0-rc1_Microsoft.AspNetCore.Http.md)
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Builder.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Builder.md
new file mode 100644
index 0000000000..2b0ba79b36
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Builder.md
@@ -0,0 +1,10 @@
+# Microsoft.AspNetCore.Builder
+
+``` diff
+ namespace Microsoft.AspNetCore.Builder {
+     public class WebSocketOptions {
++        public TimeSpan KeepAliveTimeout { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.Routing.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.Routing.md
new file mode 100644
index 0000000000..bc9ba4b8ba
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.Routing.md
@@ -0,0 +1,10 @@
+# Microsoft.AspNetCore.Components.Routing
+
+``` diff
+ namespace Microsoft.AspNetCore.Components.Routing {
+     public class FocusOnNavigate : ComponentBase {
++        protected override void BuildRenderTree(RenderTreeBuilder builder);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.Web.Virtualization.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.Web.Virtualization.md
new file mode 100644
index 0000000000..bc3afab0dc
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.Web.Virtualization.md
@@ -0,0 +1,11 @@
+# Microsoft.AspNetCore.Components.Web.Virtualization
+
+``` diff
+ namespace Microsoft.AspNetCore.Components.Web.Virtualization {
+     public sealed class Virtualize<TItem> : ComponentBase, IAsyncDisposable, IVirtualizeJsCallbacks {
++        [ParameterAttribute]
++        public int MaxItemCount { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.md
new file mode 100644
index 0000000000..cfe34b531f
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Components.md
@@ -0,0 +1,11 @@
+# Microsoft.AspNetCore.Components
+
+``` diff
+ namespace Microsoft.AspNetCore.Components {
+     public sealed class ImportMap : IComponent {
++        [ParameterAttribute(CaptureUnmatchedValues=true)]
++        public IReadOnlyDictionary<string, object>? AdditionalAttributes { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Http.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Http.md
new file mode 100644
index 0000000000..703068b088
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.AspNetCore.App/9.0-rc1_Microsoft.AspNetCore.Http.md
@@ -0,0 +1,10 @@
+# Microsoft.AspNetCore.Http
+
+``` diff
+ namespace Microsoft.AspNetCore.Http {
+     public class WebSocketAcceptContext {
++        public TimeSpan? KeepAliveTimeout { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1.md
new file mode 100644
index 0000000000..31dce18284
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1.md
@@ -0,0 +1,16 @@
+# API Difference 9.0-preview7 vs 9.0-rc1
+
+API listing follows standard diff formatting.
+Lines preceded by a '+' are additions and a '-' indicates removal.
+
+* [System](9.0-rc1_System.md)
+* [System.Collections.Generic](9.0-rc1_System.Collections.Generic.md)
+* [System.Drawing](9.0-rc1_System.Drawing.md)
+* [System.IO.Compression](9.0-rc1_System.IO.Compression.md)
+* [System.Net.WebSockets](9.0-rc1_System.Net.WebSockets.md)
+* [System.Reflection.Emit](9.0-rc1_System.Reflection.Emit.md)
+* [System.Reflection.Metadata](9.0-rc1_System.Reflection.Metadata.md)
+* [System.Runtime.Intrinsics.Arm](9.0-rc1_System.Runtime.Intrinsics.Arm.md)
+* [System.Runtime.Intrinsics.X86](9.0-rc1_System.Runtime.Intrinsics.X86.md)
+* [System.Security.Cryptography](9.0-rc1_System.Security.Cryptography.md)
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Collections.Generic.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Collections.Generic.md
new file mode 100644
index 0000000000..5052e8d504
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Collections.Generic.md
@@ -0,0 +1,21 @@
+# System.Collections.Generic
+
+``` diff
+ namespace System.Collections.Generic {
+     public static class CollectionExtensions {
+-        public static HashSet.AlternateLookup<TAlternate> GetAlternateLookup<T, TAlternate>(this HashSet<T> @set);
+-        public static Dictionary.AlternateLookup<TAlternateKey> GetAlternateLookup<TKey, TValue, TAlternateKey>(this Dictionary<TKey, TValue> dictionary);
+-        public static bool TryGetAlternateLookup<T, TAlternate>(this HashSet<T> @set, out HashSet.AlternateLookup<TAlternate> lookup);
+-        public static bool TryGetAlternateLookup<TKey, TValue, TAlternateKey>(this Dictionary<TKey, TValue> dictionary, out Dictionary.AlternateLookup<TAlternateKey> lookup);
+     }
+     public class Dictionary<TKey, TValue> : ICollection, ICollection<KeyValuePair<TKey, TValue>>, IDeserializationCallback, IDictionary, IDictionary<TKey, TValue>, IEnumerable, IEnumerable<KeyValuePair<TKey, TValue>>, IReadOnlyCollection<KeyValuePair<TKey, TValue>>, IReadOnlyDictionary<TKey, TValue>, ISerializable {
++        public Dictionary.AlternateLookup<TAlternateKey> GetAlternateLookup<TAlternateKey>();
++        public bool TryGetAlternateLookup<TAlternateKey>(out Dictionary.AlternateLookup<TAlternateKey> lookup);
+     }
+     public class HashSet<T> : ICollection<T>, IDeserializationCallback, IEnumerable, IEnumerable<T>, IReadOnlyCollection<T>, IReadOnlySet<T>, ISerializable, ISet<T> {
++        public HashSet.AlternateLookup<TAlternate> GetAlternateLookup<TAlternate>();
++        public bool TryGetAlternateLookup<TAlternate>(out HashSet.AlternateLookup<TAlternate> lookup);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Drawing.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Drawing.md
new file mode 100644
index 0000000000..fbebcbd0dd
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Drawing.md
@@ -0,0 +1,11 @@
+# System.Drawing
+
+``` diff
+ namespace System.Drawing {
+     public static class SystemColors {
++        [ExperimentalAttribute("SYSLIB5002", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++        public static bool UseAlternativeColorSet { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.IO.Compression.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.IO.Compression.md
new file mode 100644
index 0000000000..f9192afedd
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.IO.Compression.md
@@ -0,0 +1,35 @@
+# System.IO.Compression
+
+``` diff
+ namespace System.IO.Compression {
++    public sealed class BrotliCompressionOptions {
++        public BrotliCompressionOptions();
++        public int Quality { get; set; }
++    }
+     public sealed class BrotliStream : Stream {
++        public BrotliStream(Stream stream, BrotliCompressionOptions compressionOptions, bool leaveOpen = false);
+     }
+     public class DeflateStream : Stream {
++        public DeflateStream(Stream stream, ZLibCompressionOptions compressionOptions, bool leaveOpen = false);
+     }
+     public class GZipStream : Stream {
++        public GZipStream(Stream stream, ZLibCompressionOptions compressionOptions, bool leaveOpen = false);
+     }
++    public sealed class ZLibCompressionOptions {
++        public ZLibCompressionOptions();
++        public int CompressionLevel { get; set; }
++        public ZLibCompressionStrategy CompressionStrategy { get; set; }
++    }
++    public enum ZLibCompressionStrategy {
++        Default = 0,
++        Filtered = 1,
++        Fixed = 4,
++        HuffmanOnly = 2,
++        RunLengthEncoding = 3,
++    }
+     public sealed class ZLibStream : Stream {
++        public ZLibStream(Stream stream, ZLibCompressionOptions compressionOptions, bool leaveOpen = false);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Net.WebSockets.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Net.WebSockets.md
new file mode 100644
index 0000000000..dcca70d016
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Net.WebSockets.md
@@ -0,0 +1,14 @@
+# System.Net.WebSockets
+
+``` diff
+ namespace System.Net.WebSockets {
+     public sealed class ClientWebSocketOptions {
++        [UnsupportedOSPlatformAttribute("browser")]
++        public TimeSpan KeepAliveTimeout { get; set; }
+     }
+     public sealed class WebSocketCreationOptions {
++        public TimeSpan KeepAliveTimeout { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Reflection.Emit.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Reflection.Emit.md
new file mode 100644
index 0000000000..442cb3e68d
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Reflection.Emit.md
@@ -0,0 +1,19 @@
+# System.Reflection.Emit
+
+``` diff
+ namespace System.Reflection.Emit {
+     public abstract class TypeBuilder : TypeInfo {
+-        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, CallingConventions callingConvention, Type returnType, Type[]? parameterTypes);
++        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, CallingConventions callingConvention, Type? returnType, Type[]? parameterTypes);
+-        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, CallingConventions callingConvention, Type returnType, Type[]? returnTypeRequiredCustomModifiers, Type[]? returnTypeOptionalCustomModifiers, Type[]? parameterTypes, Type[][]? parameterTypeRequiredCustomModifiers, Type[][]? parameterTypeOptionalCustomModifiers);
++        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, CallingConventions callingConvention, Type? returnType, Type[]? returnTypeRequiredCustomModifiers, Type[]? returnTypeOptionalCustomModifiers, Type[]? parameterTypes, Type[][]? parameterTypeRequiredCustomModifiers, Type[][]? parameterTypeOptionalCustomModifiers);
+-        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, Type returnType, Type[]? parameterTypes);
++        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, Type? returnType, Type[]? parameterTypes);
+-        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, Type returnType, Type[]? returnTypeRequiredCustomModifiers, Type[]? returnTypeOptionalCustomModifiers, Type[]? parameterTypes, Type[][]? parameterTypeRequiredCustomModifiers, Type[][]? parameterTypeOptionalCustomModifiers);
++        public PropertyBuilder DefineProperty(string name, PropertyAttributes attributes, Type? returnType, Type[]? returnTypeRequiredCustomModifiers, Type[]? returnTypeOptionalCustomModifiers, Type[]? parameterTypes, Type[][]? parameterTypeRequiredCustomModifiers, Type[][]? parameterTypeOptionalCustomModifiers);
+-        protected abstract PropertyBuilder DefinePropertyCore(string name, PropertyAttributes attributes, CallingConventions callingConvention, Type returnType, Type[]? returnTypeRequiredCustomModifiers, Type[]? returnTypeOptionalCustomModifiers, Type[]? parameterTypes, Type[][]? parameterTypeRequiredCustomModifiers, Type[][]? parameterTypeOptionalCustomModifiers);
++        protected abstract PropertyBuilder DefinePropertyCore(string name, PropertyAttributes attributes, CallingConventions callingConvention, Type? returnType, Type[]? returnTypeRequiredCustomModifiers, Type[]? returnTypeOptionalCustomModifiers, Type[]? parameterTypes, Type[][]? parameterTypeRequiredCustomModifiers, Type[][]? parameterTypeOptionalCustomModifiers);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Reflection.Metadata.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Reflection.Metadata.md
new file mode 100644
index 0000000000..57f4d91bad
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Reflection.Metadata.md
@@ -0,0 +1,17 @@
+# System.Reflection.Metadata
+
+``` diff
+ namespace System.Reflection.Metadata {
+     public sealed class TypeName {
+-        public TypeName? DeclaringType { get; }
++        public TypeName DeclaringType { get; }
++        public TypeName MakeArrayTypeName(int rank);
++        public TypeName MakeByRefTypeName();
++        public TypeName MakeGenericTypeName(ImmutableArray<TypeName> typeArguments);
++        public TypeName MakePointerTypeName();
++        public TypeName MakeSZArrayTypeName();
++        public TypeName WithAssemblyName(AssemblyNameInfo? assemblyName);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Runtime.Intrinsics.Arm.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Runtime.Intrinsics.Arm.md
new file mode 100644
index 0000000000..f55ffd3191
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Runtime.Intrinsics.Arm.md
@@ -0,0 +1,179 @@
+# System.Runtime.Intrinsics.Arm
+
+``` diff
+ namespace System.Runtime.Intrinsics.Arm {
+-    [CLSCompliantAttribute(false)]
+-    [RequiresPreviewFeaturesAttribute("Sve is in preview. Debugger scenario is not supported.")]
+-    public abstract class Sve : AdvSimd {
++    [CLSCompliantAttribute(false)]
++    [ExperimentalAttribute("SYSLIB5003", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++    public abstract class Sve : AdvSimd {
++        public unsafe static Vector<int> GatherVectorByteZeroExtendFirstFaulting(Vector<int> mask, byte* address, Vector<int> offsets);
++        public unsafe static Vector<int> GatherVectorByteZeroExtendFirstFaulting(Vector<int> mask, byte* address, Vector<uint> offsets);
++        public unsafe static Vector<long> GatherVectorByteZeroExtendFirstFaulting(Vector<long> mask, byte* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorByteZeroExtendFirstFaulting(Vector<long> mask, byte* address, Vector<ulong> offsets);
++        public static Vector<long> GatherVectorByteZeroExtendFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<uint> GatherVectorByteZeroExtendFirstFaulting(Vector<uint> mask, byte* address, Vector<int> offsets);
++        public unsafe static Vector<uint> GatherVectorByteZeroExtendFirstFaulting(Vector<uint> mask, byte* address, Vector<uint> offsets);
++        public unsafe static Vector<ulong> GatherVectorByteZeroExtendFirstFaulting(Vector<ulong> mask, byte* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorByteZeroExtendFirstFaulting(Vector<ulong> mask, byte* address, Vector<ulong> offsets);
++        public static Vector<ulong> GatherVectorByteZeroExtendFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<double> GatherVectorFirstFaulting(Vector<double> mask, double* address, Vector<long> indices);
++        public unsafe static Vector<double> GatherVectorFirstFaulting(Vector<double> mask, double* address, Vector<ulong> indices);
++        public static Vector<double> GatherVectorFirstFaulting(Vector<double> mask, Vector<ulong> addresses);
++        public unsafe static Vector<int> GatherVectorFirstFaulting(Vector<int> mask, int* address, Vector<int> indices);
++        public unsafe static Vector<int> GatherVectorFirstFaulting(Vector<int> mask, int* address, Vector<uint> indices);
++        public unsafe static Vector<long> GatherVectorFirstFaulting(Vector<long> mask, long* address, Vector<long> indices);
++        public unsafe static Vector<long> GatherVectorFirstFaulting(Vector<long> mask, long* address, Vector<ulong> indices);
++        public static Vector<long> GatherVectorFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<float> GatherVectorFirstFaulting(Vector<float> mask, float* address, Vector<int> indices);
++        public unsafe static Vector<float> GatherVectorFirstFaulting(Vector<float> mask, float* address, Vector<uint> indices);
++        public unsafe static Vector<uint> GatherVectorFirstFaulting(Vector<uint> mask, uint* address, Vector<int> indices);
++        public unsafe static Vector<uint> GatherVectorFirstFaulting(Vector<uint> mask, uint* address, Vector<uint> indices);
++        public static Vector<ulong> GatherVectorFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<ulong> GatherVectorFirstFaulting(Vector<ulong> mask, ulong* address, Vector<long> indices);
++        public unsafe static Vector<ulong> GatherVectorFirstFaulting(Vector<ulong> mask, ulong* address, Vector<ulong> indices);
++        public unsafe static Vector<int> GatherVectorInt16SignExtendFirstFaulting(Vector<int> mask, short* address, Vector<int> indices);
++        public unsafe static Vector<int> GatherVectorInt16SignExtendFirstFaulting(Vector<int> mask, short* address, Vector<uint> indices);
++        public static Vector<int> GatherVectorInt16SignExtendFirstFaulting(Vector<int> mask, Vector<uint> addresses);
++        public unsafe static Vector<long> GatherVectorInt16SignExtendFirstFaulting(Vector<long> mask, short* address, Vector<long> indices);
++        public unsafe static Vector<long> GatherVectorInt16SignExtendFirstFaulting(Vector<long> mask, short* address, Vector<ulong> indices);
++        public static Vector<long> GatherVectorInt16SignExtendFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<uint> GatherVectorInt16SignExtendFirstFaulting(Vector<uint> mask, short* address, Vector<int> indices);
++        public unsafe static Vector<uint> GatherVectorInt16SignExtendFirstFaulting(Vector<uint> mask, short* address, Vector<uint> indices);
++        public static Vector<uint> GatherVectorInt16SignExtendFirstFaulting(Vector<uint> mask, Vector<uint> addresses);
++        public unsafe static Vector<ulong> GatherVectorInt16SignExtendFirstFaulting(Vector<ulong> mask, short* address, Vector<long> indices);
++        public unsafe static Vector<ulong> GatherVectorInt16SignExtendFirstFaulting(Vector<ulong> mask, short* address, Vector<ulong> indices);
++        public static Vector<ulong> GatherVectorInt16SignExtendFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<int> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<int> mask, short* address, Vector<int> offsets);
++        public unsafe static Vector<int> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<int> mask, short* address, Vector<uint> offsets);
++        public unsafe static Vector<long> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<long> mask, short* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<long> mask, short* address, Vector<ulong> offsets);
++        public unsafe static Vector<uint> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<uint> mask, short* address, Vector<int> offsets);
++        public unsafe static Vector<uint> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<uint> mask, short* address, Vector<uint> offsets);
++        public unsafe static Vector<ulong> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<ulong> mask, short* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorInt16WithByteOffsetsSignExtendFirstFaulting(Vector<ulong> mask, short* address, Vector<ulong> offsets);
++        public unsafe static Vector<long> GatherVectorInt32SignExtendFirstFaulting(Vector<long> mask, int* address, Vector<long> indices);
++        public unsafe static Vector<long> GatherVectorInt32SignExtendFirstFaulting(Vector<long> mask, int* address, Vector<ulong> indices);
++        public static Vector<long> GatherVectorInt32SignExtendFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<ulong> GatherVectorInt32SignExtendFirstFaulting(Vector<ulong> mask, int* address, Vector<long> indices);
++        public unsafe static Vector<ulong> GatherVectorInt32SignExtendFirstFaulting(Vector<ulong> mask, int* address, Vector<ulong> indices);
++        public static Vector<ulong> GatherVectorInt32SignExtendFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<long> GatherVectorInt32WithByteOffsetsSignExtendFirstFaulting(Vector<long> mask, int* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorInt32WithByteOffsetsSignExtendFirstFaulting(Vector<long> mask, int* address, Vector<ulong> offsets);
++        public unsafe static Vector<ulong> GatherVectorInt32WithByteOffsetsSignExtendFirstFaulting(Vector<ulong> mask, int* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorInt32WithByteOffsetsSignExtendFirstFaulting(Vector<ulong> mask, int* address, Vector<ulong> offsets);
++        public static Vector<int> GatherVectorSByteSignExtendFirstFaulting(Vector<int> mask, Vector<uint> addresses);
++        public unsafe static Vector<int> GatherVectorSByteSignExtendFirstFaulting(Vector<int> mask, sbyte* address, Vector<int> offsets);
++        public unsafe static Vector<int> GatherVectorSByteSignExtendFirstFaulting(Vector<int> mask, sbyte* address, Vector<uint> offsets);
++        public static Vector<long> GatherVectorSByteSignExtendFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<long> GatherVectorSByteSignExtendFirstFaulting(Vector<long> mask, sbyte* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorSByteSignExtendFirstFaulting(Vector<long> mask, sbyte* address, Vector<ulong> offsets);
++        public static Vector<uint> GatherVectorSByteSignExtendFirstFaulting(Vector<uint> mask, Vector<uint> addresses);
++        public unsafe static Vector<uint> GatherVectorSByteSignExtendFirstFaulting(Vector<uint> mask, sbyte* address, Vector<int> offsets);
++        public unsafe static Vector<uint> GatherVectorSByteSignExtendFirstFaulting(Vector<uint> mask, sbyte* address, Vector<uint> offsets);
++        public static Vector<ulong> GatherVectorSByteSignExtendFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<ulong> GatherVectorSByteSignExtendFirstFaulting(Vector<ulong> mask, sbyte* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorSByteSignExtendFirstFaulting(Vector<ulong> mask, sbyte* address, Vector<ulong> offsets);
++        public unsafe static Vector<int> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<int> mask, ushort* address, Vector<int> offsets);
++        public unsafe static Vector<int> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<int> mask, ushort* address, Vector<uint> offsets);
++        public unsafe static Vector<long> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<long> mask, ushort* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<long> mask, ushort* address, Vector<ulong> offsets);
++        public unsafe static Vector<uint> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<uint> mask, ushort* address, Vector<int> offsets);
++        public unsafe static Vector<uint> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<uint> mask, ushort* address, Vector<uint> offsets);
++        public unsafe static Vector<ulong> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<ulong> mask, ushort* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorUInt16WithByteOffsetsZeroExtendFirstFaulting(Vector<ulong> mask, ushort* address, Vector<ulong> offsets);
++        public unsafe static Vector<int> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<int> mask, ushort* address, Vector<int> indices);
++        public unsafe static Vector<int> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<int> mask, ushort* address, Vector<uint> indices);
++        public static Vector<long> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<long> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<long> mask, ushort* address, Vector<long> indices);
++        public unsafe static Vector<long> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<long> mask, ushort* address, Vector<ulong> indices);
++        public unsafe static Vector<uint> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<uint> mask, ushort* address, Vector<int> indices);
++        public unsafe static Vector<uint> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<uint> mask, ushort* address, Vector<uint> indices);
++        public static Vector<ulong> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<ulong> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<ulong> mask, ushort* address, Vector<long> indices);
++        public unsafe static Vector<ulong> GatherVectorUInt16ZeroExtendFirstFaulting(Vector<ulong> mask, ushort* address, Vector<ulong> indices);
++        public unsafe static Vector<int> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<int> mask, uint* address, Vector<int> offsets);
++        public unsafe static Vector<int> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<int> mask, uint* address, Vector<uint> offsets);
++        public unsafe static Vector<long> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<long> mask, uint* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<long> mask, uint* address, Vector<ulong> offsets);
++        public unsafe static Vector<uint> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<uint> mask, uint* address, Vector<int> offsets);
++        public unsafe static Vector<uint> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<uint> mask, uint* address, Vector<uint> offsets);
++        public unsafe static Vector<ulong> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<ulong> mask, uint* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorUInt32WithByteOffsetsZeroExtendFirstFaulting(Vector<ulong> mask, uint* address, Vector<ulong> offsets);
++        public unsafe static Vector<int> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<int> mask, uint* address, Vector<int> indices);
++        public unsafe static Vector<int> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<int> mask, uint* address, Vector<uint> indices);
++        public static Vector<long> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<long> mask, Vector<ulong> addresses);
++        public unsafe static Vector<long> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<long> mask, uint* address, Vector<long> indices);
++        public unsafe static Vector<long> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<long> mask, uint* address, Vector<ulong> indices);
++        public unsafe static Vector<uint> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<uint> mask, uint* address, Vector<int> indices);
++        public unsafe static Vector<uint> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<uint> mask, uint* address, Vector<uint> indices);
++        public static Vector<ulong> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<ulong> mask, Vector<ulong> addresses);
++        public unsafe static Vector<ulong> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<ulong> mask, uint* address, Vector<long> indices);
++        public unsafe static Vector<ulong> GatherVectorUInt32ZeroExtendFirstFaulting(Vector<ulong> mask, uint* address, Vector<ulong> indices);
++        public unsafe static Vector<double> GatherVectorWithByteOffsetFirstFaulting(Vector<double> mask, double* address, Vector<long> offsets);
++        public unsafe static Vector<double> GatherVectorWithByteOffsetFirstFaulting(Vector<double> mask, double* address, Vector<ulong> offsets);
++        public unsafe static Vector<int> GatherVectorWithByteOffsetFirstFaulting(Vector<int> mask, int* address, Vector<int> offsets);
++        public unsafe static Vector<int> GatherVectorWithByteOffsetFirstFaulting(Vector<int> mask, int* address, Vector<uint> offsets);
++        public unsafe static Vector<long> GatherVectorWithByteOffsetFirstFaulting(Vector<long> mask, long* address, Vector<long> offsets);
++        public unsafe static Vector<long> GatherVectorWithByteOffsetFirstFaulting(Vector<long> mask, long* address, Vector<ulong> offsets);
++        public unsafe static Vector<float> GatherVectorWithByteOffsetFirstFaulting(Vector<float> mask, float* address, Vector<int> offsets);
++        public unsafe static Vector<float> GatherVectorWithByteOffsetFirstFaulting(Vector<float> mask, float* address, Vector<uint> offsets);
++        public unsafe static Vector<uint> GatherVectorWithByteOffsetFirstFaulting(Vector<uint> mask, uint* address, Vector<int> offsets);
++        public unsafe static Vector<uint> GatherVectorWithByteOffsetFirstFaulting(Vector<uint> mask, uint* address, Vector<uint> offsets);
++        public unsafe static Vector<ulong> GatherVectorWithByteOffsetFirstFaulting(Vector<ulong> mask, ulong* address, Vector<long> offsets);
++        public unsafe static Vector<ulong> GatherVectorWithByteOffsetFirstFaulting(Vector<ulong> mask, ulong* address, Vector<ulong> offsets);
++        public static Vector<byte> GetFfrByte();
++        public static Vector<short> GetFfrInt16();
++        public static Vector<int> GetFfrInt32();
++        public static Vector<long> GetFfrInt64();
++        public static Vector<sbyte> GetFfrSByte();
++        public static Vector<ushort> GetFfrUInt16();
++        public static Vector<uint> GetFfrUInt32();
++        public static Vector<ulong> GetFfrUInt64();
++        public unsafe static Vector<short> LoadVectorByteZeroExtendFirstFaulting(Vector<short> mask, byte* address);
++        public unsafe static Vector<int> LoadVectorByteZeroExtendFirstFaulting(Vector<int> mask, byte* address);
++        public unsafe static Vector<long> LoadVectorByteZeroExtendFirstFaulting(Vector<long> mask, byte* address);
++        public unsafe static Vector<ushort> LoadVectorByteZeroExtendFirstFaulting(Vector<ushort> mask, byte* address);
++        public unsafe static Vector<uint> LoadVectorByteZeroExtendFirstFaulting(Vector<uint> mask, byte* address);
++        public unsafe static Vector<ulong> LoadVectorByteZeroExtendFirstFaulting(Vector<ulong> mask, byte* address);
++        public unsafe static Vector<byte> LoadVectorFirstFaulting(Vector<byte> mask, byte* address);
++        public unsafe static Vector<double> LoadVectorFirstFaulting(Vector<double> mask, double* address);
++        public unsafe static Vector<short> LoadVectorFirstFaulting(Vector<short> mask, short* address);
++        public unsafe static Vector<int> LoadVectorFirstFaulting(Vector<int> mask, int* address);
++        public unsafe static Vector<long> LoadVectorFirstFaulting(Vector<long> mask, long* address);
++        public unsafe static Vector<sbyte> LoadVectorFirstFaulting(Vector<sbyte> mask, sbyte* address);
++        public unsafe static Vector<float> LoadVectorFirstFaulting(Vector<float> mask, float* address);
++        public unsafe static Vector<ushort> LoadVectorFirstFaulting(Vector<ushort> mask, ushort* address);
++        public unsafe static Vector<uint> LoadVectorFirstFaulting(Vector<uint> mask, uint* address);
++        public unsafe static Vector<ulong> LoadVectorFirstFaulting(Vector<ulong> mask, ulong* address);
++        public unsafe static Vector<int> LoadVectorInt16SignExtendFirstFaulting(Vector<int> mask, short* address);
++        public unsafe static Vector<long> LoadVectorInt16SignExtendFirstFaulting(Vector<long> mask, short* address);
++        public unsafe static Vector<uint> LoadVectorInt16SignExtendFirstFaulting(Vector<uint> mask, short* address);
++        public unsafe static Vector<ulong> LoadVectorInt16SignExtendFirstFaulting(Vector<ulong> mask, short* address);
++        public unsafe static Vector<long> LoadVectorInt32SignExtendFirstFaulting(Vector<long> mask, int* address);
++        public unsafe static Vector<ulong> LoadVectorInt32SignExtendFirstFaulting(Vector<ulong> mask, int* address);
++        public unsafe static Vector<short> LoadVectorSByteSignExtendFirstFaulting(Vector<short> mask, sbyte* address);
++        public unsafe static Vector<int> LoadVectorSByteSignExtendFirstFaulting(Vector<int> mask, sbyte* address);
++        public unsafe static Vector<long> LoadVectorSByteSignExtendFirstFaulting(Vector<long> mask, sbyte* address);
++        public unsafe static Vector<ushort> LoadVectorSByteSignExtendFirstFaulting(Vector<ushort> mask, sbyte* address);
++        public unsafe static Vector<uint> LoadVectorSByteSignExtendFirstFaulting(Vector<uint> mask, sbyte* address);
++        public unsafe static Vector<ulong> LoadVectorSByteSignExtendFirstFaulting(Vector<ulong> mask, sbyte* address);
++        public unsafe static Vector<int> LoadVectorUInt16ZeroExtendFirstFaulting(Vector<int> mask, ushort* address);
++        public unsafe static Vector<long> LoadVectorUInt16ZeroExtendFirstFaulting(Vector<long> mask, ushort* address);
++        public unsafe static Vector<uint> LoadVectorUInt16ZeroExtendFirstFaulting(Vector<uint> mask, ushort* address);
++        public unsafe static Vector<ulong> LoadVectorUInt16ZeroExtendFirstFaulting(Vector<ulong> mask, ushort* address);
++        public unsafe static Vector<long> LoadVectorUInt32ZeroExtendFirstFaulting(Vector<long> mask, uint* address);
++        public unsafe static Vector<ulong> LoadVectorUInt32ZeroExtendFirstFaulting(Vector<ulong> mask, uint* address);
++        public static void SetFfr(Vector<byte> value);
++        public static void SetFfr(Vector<short> value);
++        public static void SetFfr(Vector<int> value);
++        public static void SetFfr(Vector<long> value);
++        public static void SetFfr(Vector<sbyte> value);
++        public static void SetFfr(Vector<ushort> value);
++        public static void SetFfr(Vector<uint> value);
++        public static void SetFfr(Vector<ulong> value);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Runtime.Intrinsics.X86.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Runtime.Intrinsics.X86.md
new file mode 100644
index 0000000000..fcff53d79f
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Runtime.Intrinsics.X86.md
@@ -0,0 +1,41 @@
+# System.Runtime.Intrinsics.X86
+
+``` diff
+ namespace System.Runtime.Intrinsics.X86 {
+-    [CLSCompliantAttribute(false)]
+-    [RequiresPreviewFeaturesAttribute("AvxVnni is in preview.")]
+-    public abstract class AvxVnni : Avx2
++    [CLSCompliantAttribute(false)]
++    public abstract class AvxVnni : Avx2
+     [CLSCompliantAttribute(false)]
+     public abstract class X86Base {
+-        [RequiresPreviewFeaturesAttribute("DivRem is in preview.")]
+-        public static (int Quotient, int Remainder) DivRem(uint lower, int upper, int divisor);
++        [ExperimentalAttribute("SYSLIB5004", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++        public static (int Quotient, int Remainder) DivRem(uint lower, int upper, int divisor);
+-        [RequiresPreviewFeaturesAttribute("DivRem is in preview.")]
+-        public static (uint Quotient, uint Remainder) DivRem(uint lower, uint upper, uint divisor);
++        [ExperimentalAttribute("SYSLIB5004", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++        public static (uint Quotient, uint Remainder) DivRem(uint lower, uint upper, uint divisor);
+-        [RequiresPreviewFeaturesAttribute("DivRem is in preview.")]
+-        public static (IntPtr Quotient, IntPtr Remainder) DivRem(UIntPtr lower, IntPtr upper, IntPtr divisor);
++        [ExperimentalAttribute("SYSLIB5004", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++        public static (IntPtr Quotient, IntPtr Remainder) DivRem(UIntPtr lower, IntPtr upper, IntPtr divisor);
+-        [RequiresPreviewFeaturesAttribute("DivRem is in preview.")]
+-        public static (UIntPtr Quotient, UIntPtr Remainder) DivRem(UIntPtr lower, UIntPtr upper, UIntPtr divisor);
++        [ExperimentalAttribute("SYSLIB5004", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++        public static (UIntPtr Quotient, UIntPtr Remainder) DivRem(UIntPtr lower, UIntPtr upper, UIntPtr divisor);
+         public abstract class X64 {
+-            [RequiresPreviewFeaturesAttribute("DivRem is in preview.")]
+-            public static (long Quotient, long Remainder) DivRem(ulong lower, long upper, long divisor);
++            [ExperimentalAttribute("SYSLIB5004", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++            public static (long Quotient, long Remainder) DivRem(ulong lower, long upper, long divisor);
+-            [RequiresPreviewFeaturesAttribute("DivRem is in preview.")]
+-            public static (ulong Quotient, ulong Remainder) DivRem(ulong lower, ulong upper, ulong divisor);
++            [ExperimentalAttribute("SYSLIB5004", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
++            public static (ulong Quotient, ulong Remainder) DivRem(ulong lower, ulong upper, ulong divisor);
+         }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Security.Cryptography.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Security.Cryptography.md
new file mode 100644
index 0000000000..7de128a17d
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.Security.Cryptography.md
@@ -0,0 +1,33 @@
+# System.Security.Cryptography
+
+``` diff
+ namespace System.Security.Cryptography {
+-    [SupportedOSPlatformAttribute("ios13.0")]
+-    [SupportedOSPlatformAttribute("maccatalyst")]
+-    [SupportedOSPlatformAttribute("tvos13.0")]
+-    [UnsupportedOSPlatformAttribute("browser")]
+-    [UnsupportedOSPlatformAttribute("ios")]
+-    [UnsupportedOSPlatformAttribute("tvos")]
+-    public sealed class AesGcm : IDisposable
++    [SupportedOSPlatformAttribute("ios13.0")]
++    [SupportedOSPlatformAttribute("tvos13.0")]
++    [UnsupportedOSPlatformAttribute("browser")]
++    [UnsupportedOSPlatformAttribute("ios")]
++    [UnsupportedOSPlatformAttribute("tvos")]
++    public sealed class AesGcm : IDisposable
+-    [SupportedOSPlatformAttribute("ios13.0")]
+-    [SupportedOSPlatformAttribute("maccatalyst")]
+-    [SupportedOSPlatformAttribute("tvos13.0")]
+-    [UnsupportedOSPlatformAttribute("browser")]
+-    [UnsupportedOSPlatformAttribute("ios")]
+-    [UnsupportedOSPlatformAttribute("tvos")]
+-    public sealed class ChaCha20Poly1305 : IDisposable
++    [SupportedOSPlatformAttribute("ios13.0")]
++    [SupportedOSPlatformAttribute("tvos13.0")]
++    [UnsupportedOSPlatformAttribute("browser")]
++    [UnsupportedOSPlatformAttribute("ios")]
++    [UnsupportedOSPlatformAttribute("tvos")]
++    public sealed class ChaCha20Poly1305 : IDisposable
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.md
new file mode 100644
index 0000000000..3bc9a8650a
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.NETCore.App/9.0-rc1_System.md
@@ -0,0 +1,28 @@
+# System
+
+``` diff
+ namespace System {
+     public static class Console {
+-        [UnsupportedOSPlatformAttribute("android")]
+-        [UnsupportedOSPlatformAttribute("browser")]
+-        [UnsupportedOSPlatformAttribute("ios")]
+-        [UnsupportedOSPlatformAttribute("tvos")]
+-        public static int WindowHeight { get; set; }
++        public static int WindowHeight { [UnsupportedOSPlatformAttribute("android"), UnsupportedOSPlatformAttribute("browser"), UnsupportedOSPlatformAttribute("ios"), UnsupportedOSPlatformAttribute("tvos")] get; [SupportedOSPlatformAttribute("windows")] set; }
+-        [UnsupportedOSPlatformAttribute("android")]
+-        [UnsupportedOSPlatformAttribute("browser")]
+-        [UnsupportedOSPlatformAttribute("ios")]
+-        [UnsupportedOSPlatformAttribute("tvos")]
+-        public static int WindowWidth { get; set; }
++        public static int WindowWidth { [UnsupportedOSPlatformAttribute("android"), UnsupportedOSPlatformAttribute("browser"), UnsupportedOSPlatformAttribute("ios"), UnsupportedOSPlatformAttribute("tvos")] get; [SupportedOSPlatformAttribute("windows")] set; }
+-        [UnsupportedOSPlatformAttribute("android")]
+-        [UnsupportedOSPlatformAttribute("browser")]
+-        [UnsupportedOSPlatformAttribute("ios")]
+-        [UnsupportedOSPlatformAttribute("tvos")]
+-        public static void SetWindowSize(int width, int height);
++        [SupportedOSPlatformAttribute("windows")]
++        public static void SetWindowSize(int width, int height);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1.md
new file mode 100644
index 0000000000..5e7dd10354
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1.md
@@ -0,0 +1,9 @@
+# API Difference 9.0-preview7 vs 9.0-rc1
+
+API listing follows standard diff formatting.
+Lines preceded by a '+' are additions and a '-' indicates removal.
+
+* [Microsoft.VisualBasic.ApplicationServices](9.0-rc1_Microsoft.VisualBasic.ApplicationServices.md)
+* [System.Windows](9.0-rc1_System.Windows.md)
+* [System.Windows.Forms](9.0-rc1_System.Windows.Forms.md)
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_Microsoft.VisualBasic.ApplicationServices.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_Microsoft.VisualBasic.ApplicationServices.md
new file mode 100644
index 0000000000..9d729386e1
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_Microsoft.VisualBasic.ApplicationServices.md
@@ -0,0 +1,18 @@
+# Microsoft.VisualBasic.ApplicationServices
+
+``` diff
+ namespace Microsoft.VisualBasic.ApplicationServices {
+     [ComVisibleAttribute(false)]
+     [EditorBrowsableAttribute(2)]
+     public class ApplyApplicationDefaultsEventArgs : EventArgs {
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-experimental/{0}")]
++        public SystemColorMode ColorMode { get; set; }
+     }
+     public class WindowsFormsApplicationBase : ConsoleApplicationBase {
++        [EditorBrowsableAttribute(1)]
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-experimental/{0}")]
++        protected SystemColorMode ColorMode { get; set; }
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_System.Windows.Forms.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_System.Windows.Forms.md
new file mode 100644
index 0000000000..7b7b58d7ae
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_System.Windows.Forms.md
@@ -0,0 +1,124 @@
+# System.Windows.Forms
+
+``` diff
+ namespace System.Windows.Forms {
+     public sealed class Application {
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static SystemColorMode ColorMode { get; }
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static bool IsDarkModeEnabled { get; }
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static SystemColorMode SystemColorMode { get; }
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static void SetColorMode(SystemColorMode systemColorMode);
+     }
+     [DefaultEventAttribute("Click")]
+     [DefaultPropertyAttribute("Text")]
+     [DesignerAttribute("System.Windows.Forms.Design.ControlDesigner, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")]
+     [DesignerSerializerAttribute("System.Windows.Forms.Design.ControlCodeDomSerializer, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", "System.ComponentModel.Design.Serialization.CodeDomSerializer, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")]
+     [ToolboxItemFilterAttribute("System.Windows.Forms")]
+     public class Control : Component, IArrangedElement, IBindableComponent, IComponent, IDisposable, IDropTarget, IHandle<HWND>, IKeyboardToolTip, IOleControl.Interface, IOleInPlaceActiveObject.Interface, IOleInPlaceObject.Interface, IOleObject.Interface, IOleWindow.Interface, IPersist.Interface, IPersistPropertyBag.Interface, IPersistStorage.Interface, IPersistStreamInit.Interface, IQuickActivate.Interface, ISupportOleDropSource, ISynchronizeInvoke, IViewObject.Interface, IViewObject2.Interface, IWin32Window {
++        public Task InvokeAsync(Action callback, CancellationToken cancellationToken = default(CancellationToken));
++        public Task InvokeAsync(Func<CancellationToken, ValueTask> callback, CancellationToken cancellationToken = default(CancellationToken));
++        public Task<T> InvokeAsync<T>(Func<CancellationToken, ValueTask<T>> callback, CancellationToken cancellationToken = default(CancellationToken));
++        public Task<T> InvokeAsync<T>(Func<T> callback, CancellationToken cancellationToken = default(CancellationToken));
+     }
+     [FlagsAttribute]
+     public enum ControlStyles {
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        ApplyThemingImplicitly = 524288,
+     }
+     [DefaultEventAttribute("Load")]
+     [DesignTimeVisibleAttribute(false)]
+     [DesignerAttribute("System.Windows.Forms.Design.FormDocumentDesigner, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(IRootDesigner))]
+     [DesignerCategoryAttribute("Form")]
+     [InitializationEventAttribute("Load")]
+     [ToolboxItemAttribute(false)]
+     [ToolboxItemFilterAttribute("System.Windows.Forms.Control.TopLevel")]
+     public class Form : ContainerControl {
++        [BrowsableAttribute(false)]
++        [DesignerSerializationVisibilityAttribute(0)]
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatWindowStyle")]
++        [SRDescriptionAttribute("FormBorderColorDescr")]
++        public Color FormBorderColor { get; set; }
++        [BrowsableAttribute(false)]
++        [DesignerSerializationVisibilityAttribute(0)]
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatWindowStyle")]
++        [SRDescriptionAttribute("FormCaptionBackColorDescr")]
++        public Color FormCaptionBackColor { get; set; }
++        [BrowsableAttribute(false)]
++        [DesignerSerializationVisibilityAttribute(0)]
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatWindowStyle")]
++        [SRDescriptionAttribute("FormCaptionTextColorDescr")]
++        public Color FormCaptionTextColor { get; set; }
++        [BrowsableAttribute(false)]
++        [DefaultValueAttribute(FormCornerPreference.Default)]
++        [DesignerSerializationVisibilityAttribute(0)]
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatWindowStyle")]
++        [SRDescriptionAttribute("FormCornerPreferenceDescr")]
++        public FormCornerPreference FormCornerPreference { get; set; }
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatAppearance")]
++        [SRDescriptionAttribute("FormBorderColorChangedDescr")]
++        public event EventHandler FormBorderColorChanged;
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatAppearance")]
++        [SRDescriptionAttribute("FormCaptionBackColorChangedDescr")]
++        public event EventHandler FormCaptionBackColorChanged;
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatAppearance")]
++        [SRDescriptionAttribute("FormCaptionTextColorChangedDescr")]
++        public event EventHandler FormCaptionTextColorChanged;
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        [SRCategoryAttribute("CatAppearance")]
++        [SRDescriptionAttribute("FormCornerPreferenceChangedDescr")]
++        public event EventHandler FormCornerPreferenceChanged;
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        protected virtual void OnFormBorderColorChanged(EventArgs e);
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        protected virtual void OnFormCaptionBackColorChanged(EventArgs e);
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        protected virtual void OnFormCaptionTextColorChanged(EventArgs e);
++        [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        protected virtual void OnFormCornerPreferenceChanged(EventArgs e);
++        [ExperimentalAttribute("WFO5002", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public Task ShowAsync(IWin32Window? owner = null);
++        [ExperimentalAttribute("WFO5002", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public Task<DialogResult> ShowDialogAsync();
++        [ExperimentalAttribute("WFO5002", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public Task<DialogResult> ShowDialogAsync(IWin32Window owner);
+     }
++    [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++    public enum FormCornerPreference {
++        Default = 0,
++        DoNotRound = 1,
++        Round = 2,
++        RoundSmall = 3,
++    }
+     [DefaultBindingPropertyAttribute("Value")]
+     [DefaultPropertyAttribute("Value")]
+     [SRDescriptionAttribute("DescriptionProgressBar")]
+     public class ProgressBar : Control {
++        protected override void OnCreateControl();
+     }
++    [ExperimentalAttribute("WFO5001", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++    public enum SystemColorMode {
++        Classic = 0,
++        Dark = 2,
++        System = 1,
++    }
+     public class TaskDialog : IWin32Window {
++        [ExperimentalAttribute("WFO5002", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static Task<TaskDialogButton> ShowDialogAsync(IntPtr hwndOwner, TaskDialogPage page, TaskDialogStartupLocation startupLocation = TaskDialogStartupLocation.CenterOwner);
++        [ExperimentalAttribute("WFO5002", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static Task<TaskDialogButton> ShowDialogAsync(IWin32Window owner, TaskDialogPage page, TaskDialogStartupLocation startupLocation = TaskDialogStartupLocation.CenterOwner);
++        [ExperimentalAttribute("WFO5002", UrlFormat="https://aka.ms/winforms-warnings/{0}")]
++        public static Task<TaskDialogButton> ShowDialogAsync(TaskDialogPage page, TaskDialogStartupLocation startupLocation = TaskDialogStartupLocation.CenterScreen);
+     }
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_System.Windows.md b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_System.Windows.md
new file mode 100644
index 0000000000..ec76a6f4e6
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/Microsoft.WindowsDesktop.App/9.0-rc1_System.Windows.md
@@ -0,0 +1,14 @@
+# System.Windows
+
+``` diff
+ namespace System.Windows {
+-    [ContentPropertyAttribute("Value")]
+-    [XamlSetMarkupExtensionAttribute("ReceiveMarkupExtension")]
+-    [XamlSetTypeConverterAttribute("ReceiveTypeConverter")]
+-    public class Setter : SetterBase, ISupportInitialize
++    [XamlSetMarkupExtensionAttribute("ReceiveMarkupExtension")]
++    [XamlSetTypeConverterAttribute("ReceiveTypeConverter")]
++    public class Setter : SetterBase, ISupportInitialize
+ }
+```
+
diff --git a/release-notes/9.0/preview/rc1/api-diff/README.md b/release-notes/9.0/preview/rc1/api-diff/README.md
new file mode 100644
index 0000000000..d28a14d81d
--- /dev/null
+++ b/release-notes/9.0/preview/rc1/api-diff/README.md
@@ -0,0 +1,7 @@
+# .NET 9.0 RC 1 API Changes
+
+The following API changes were made in .NET 9.0 RC 1:
+
+- [Microsoft.NETCore.App](./Microsoft.NETCore.App/9.0-rc1.md)
+- [Microsoft.AspNetCore.App](./Microsoft.AspNetCore.App/9.0-rc1.md)
+- [Microsoft.WindowsDesktop.App](./Microsoft.WindowsDesktop.App/9.0-rc1.md)