diff --git a/release-notes/3.0/preview/api-diff/rc1/Asp.Net/3.0-rc1.md b/release-notes/3.0/preview/api-diff/rc1/Asp.Net/3.0-rc1.md
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+++ b/release-notes/3.0/preview/api-diff/rc1/Asp.Net/3.0-rc1.md
@@ -0,0 +1,7 @@
+# API Difference aspnetcoreapp3.0-preview9 vs aspnetcoreapp3.0-rc1
+
+API listing follows standard diff formatting. Lines preceded by a '+' are
+additions and a '-' indicates removal.
+
+* [Microsoft.AspNetCore.Components.RenderTree](3.0-rc1_Microsoft.AspNetCore.Components.RenderTree.md)
+
diff --git a/release-notes/3.0/preview/api-diff/rc1/Asp.Net/3.0-rc1_Microsoft.AspNetCore.Components.RenderTree.md b/release-notes/3.0/preview/api-diff/rc1/Asp.Net/3.0-rc1_Microsoft.AspNetCore.Components.RenderTree.md
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+++ b/release-notes/3.0/preview/api-diff/rc1/Asp.Net/3.0-rc1_Microsoft.AspNetCore.Components.RenderTree.md
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+# Microsoft.AspNetCore.Components.RenderTree
+
+``` diff
+ namespace Microsoft.AspNetCore.Components.RenderTree {
+     public readonly struct RenderTreeFrame {
+-        [System.Runtime.InteropServices.FieldOffsetAttribute(8)]
+-        public readonly int AttributeEventHandlerId;
+
++        [System.Runtime.InteropServices.FieldOffsetAttribute(32)]
++        public readonly object ComponentKey;
++        [System.Runtime.InteropServices.FieldOffsetAttribute(24)]
++        public readonly object ElementKey;
++        [System.Runtime.InteropServices.FieldOffsetAttribute(32)]
++        public readonly string AttributeEventUpdatesAttributeName;
++        [System.Runtime.InteropServices.FieldOffsetAttribute(8)]
++        public readonly ulong AttributeEventHandlerId;
+     }
+ }
+```
+
diff --git a/release-notes/3.0/preview/api-diff/rc1/README.md b/release-notes/3.0/preview/api-diff/rc1/README.md
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+++ b/release-notes/3.0/preview/api-diff/rc1/README.md
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+# .NET Core 3.0 rc1 API Changes
+
+The following API changes were made in .NET Core 3.0 rc1:
+
+- [ASP.NET Core](./Asp.Net/3.0-rc1.md)