diff --git a/build/dependencies.props b/build/dependencies.props
index cd08bf7dfa..28e797542e 100644
--- a/build/dependencies.props
+++ b/build/dependencies.props
@@ -65,7 +65,7 @@
     <MicrosoftOwinSecurityCookiesPackageVersion>3.0.1</MicrosoftOwinSecurityCookiesPackageVersion>
     <MicrosoftOwinSecurityInteropPackageVersion>2.1.0-preview3-32037</MicrosoftOwinSecurityInteropPackageVersion>
     <MoqPackageVersion>4.7.49</MoqPackageVersion>
-    <SystemComponentModelAnnotationsPackageVersion>4.5.0-preview2-26313-01</SystemComponentModelAnnotationsPackageVersion>
+    <SystemComponentModelAnnotationsPackageVersion>4.5.0-preview2-26326-04</SystemComponentModelAnnotationsPackageVersion>
     <XunitAnalyzersPackageVersion>0.8.0</XunitAnalyzersPackageVersion>
     <XunitPackageVersion>2.3.1</XunitPackageVersion>
     <XunitRunnerVisualStudioPackageVersion>2.4.0-beta.1.build3945</XunitRunnerVisualStudioPackageVersion>
diff --git a/src/Core/Microsoft.Extensions.Identity.Core.csproj b/src/Core/Microsoft.Extensions.Identity.Core.csproj
index f73848a02d..c446217071 100644
--- a/src/Core/Microsoft.Extensions.Identity.Core.csproj
+++ b/src/Core/Microsoft.Extensions.Identity.Core.csproj
@@ -5,7 +5,6 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;identity;membership</PackageTags>
-    <EnableApiCheck>false</EnableApiCheck>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Core/UserManager.cs b/src/Core/UserManager.cs
index 5d67f1f096..7e5b6832fa 100644
--- a/src/Core/UserManager.cs
+++ b/src/Core/UserManager.cs
@@ -2224,11 +2224,7 @@ namespace Microsoft.AspNetCore.Identity
         /// </summary>
         /// <returns>The new security secret.</returns>
         public virtual string GenerateNewAuthenticatorKey()
-        {
-            byte[] bytes = new byte[20];
-            _rng.GetBytes(bytes);
-            return Base32.ToBase32(bytes);
-        }
+            => NewSecurityStamp();
 
         /// <summary>
         /// Generates recovery codes for the user, this invalidates any previous recovery codes for the user.
@@ -2419,7 +2415,9 @@ namespace Microsoft.AspNetCore.Identity
 
         private static string NewSecurityStamp()
         {
-            return Guid.NewGuid().ToString();
+            byte[] bytes = new byte[20];
+            _rng.GetBytes(bytes);
+            return Base32.ToBase32(bytes);
         }
 
         // IUserLoginStore methods
diff --git a/src/Core/breakingchanges.netcore.json b/src/Core/breakingchanges.netcore.json
new file mode 100644
index 0000000000..3540ff03a1
--- /dev/null
+++ b/src/Core/breakingchanges.netcore.json
@@ -0,0 +1,17 @@
+  [
+    {
+      "TypeId": "public class Microsoft.AspNetCore.Identity.UserManager<T0> : System.IDisposable where T0 : class",
+      "MemberId": "protected const System.String ChangePhoneNumberTokenPurpose = \"ChangePhoneNumber\"",
+      "Kind": "Removal"
+    },
+    {
+      "TypeId": "public class Microsoft.AspNetCore.Identity.UserManager<T0> : System.IDisposable where T0 : class",
+      "MemberId": "protected const System.String ConfirmEmailTokenPurpose = \"EmailConfirmation\"",
+      "Kind": "Removal"
+    },
+    {
+      "TypeId": "public class Microsoft.AspNetCore.Identity.UserManager<T0> : System.IDisposable where T0 : class",
+      "MemberId": "protected const System.String ResetPasswordTokenPurpose = \"ResetPassword\"",
+      "Kind": "Removal"
+    }
+  ]
\ No newline at end of file
diff --git a/src/Identity/Microsoft.AspNetCore.Identity.csproj b/src/Identity/Microsoft.AspNetCore.Identity.csproj
index 6d83fe847b..fc0fae70c8 100644
--- a/src/Identity/Microsoft.AspNetCore.Identity.csproj
+++ b/src/Identity/Microsoft.AspNetCore.Identity.csproj
@@ -5,7 +5,6 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;identity;membership</PackageTags>
-    <EnableApiCheck>false</EnableApiCheck>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Stores/Microsoft.Extensions.Identity.Stores.csproj b/src/Stores/Microsoft.Extensions.Identity.Stores.csproj
index 0a792aeca2..10e6e98997 100644
--- a/src/Stores/Microsoft.Extensions.Identity.Stores.csproj
+++ b/src/Stores/Microsoft.Extensions.Identity.Stores.csproj
@@ -5,7 +5,6 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;identity;membership</PackageTags>
-    <EnableApiCheck>false</EnableApiCheck>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/UI/Microsoft.AspNetCore.Identity.UI.csproj b/src/UI/Microsoft.AspNetCore.Identity.UI.csproj
index e81d9c1a8d..90fbc7c140 100644
--- a/src/UI/Microsoft.AspNetCore.Identity.UI.csproj
+++ b/src/UI/Microsoft.AspNetCore.Identity.UI.csproj
@@ -6,7 +6,6 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <GenerateDocumentationFile>false</GenerateDocumentationFile>
     <PackageTags>aspnetcore;identity;membership;razorpages</PackageTags>
-    <EnableApiCheck>false</EnableApiCheck>
     <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
     <ProvideApplicationPartFactoryAttributeTypeName>Microsoft.AspNetCore.Mvc.ApplicationParts.NullApplicationPartFactory, Microsoft.AspNetCore.Mvc.Core</ProvideApplicationPartFactoryAttributeTypeName>
   </PropertyGroup>
diff --git a/src/UI/baseline.netcore.json b/src/UI/baseline.netcore.json
new file mode 100644
index 0000000000..7a73a41bfd
--- /dev/null
+++ b/src/UI/baseline.netcore.json
@@ -0,0 +1,2 @@
+{
+}
\ No newline at end of file