diff --git a/build/dependencies.props b/build/dependencies.props
index 232d99adcd..8507e0d2bf 100644
--- a/build/dependencies.props
+++ b/build/dependencies.props
@@ -31,7 +31,7 @@
     <MicrosoftAspNetCoreTestHostPackageVersion>2.1.0-preview1-27942</MicrosoftAspNetCoreTestHostPackageVersion>
     <MicrosoftAspNetCoreTestingPackageVersion>2.1.0-preview1-27942</MicrosoftAspNetCoreTestingPackageVersion>
     <MicrosoftAspNetCoreWebSocketsPackageVersion>2.1.0-preview1-27942</MicrosoftAspNetCoreWebSocketsPackageVersion>
-    <MicrosoftCSharpPackageVersion>4.5.0-preview1-26016-05</MicrosoftCSharpPackageVersion>
+    <MicrosoftCSharpPackageVersion>4.5.0-preview1-26102-01</MicrosoftCSharpPackageVersion>
     <MicrosoftEntityFrameworkCoreDesignPackageVersion>2.1.0-preview1-27942</MicrosoftEntityFrameworkCoreDesignPackageVersion>
     <MicrosoftEntityFrameworkCoreSqlServerPackageVersion>2.1.0-preview1-27942</MicrosoftEntityFrameworkCoreSqlServerPackageVersion>
     <MicrosoftEntityFrameworkCoreToolsPackageVersion>2.1.0-preview1-27942</MicrosoftEntityFrameworkCoreToolsPackageVersion>
@@ -53,21 +53,21 @@
     <MicrosoftExtensionsSecurityHelperSourcesPackageVersion>2.1.0-preview1-27942</MicrosoftExtensionsSecurityHelperSourcesPackageVersion>
     <MicrosoftExtensionsValueStopwatchSourcesPackageVersion>2.1.0-preview1-27942</MicrosoftExtensionsValueStopwatchSourcesPackageVersion>
     <MicrosoftNETCoreApp20PackageVersion>2.0.0</MicrosoftNETCoreApp20PackageVersion>
-    <MicrosoftNETCoreApp21PackageVersion>2.1.0-preview1-26016-05</MicrosoftNETCoreApp21PackageVersion>
+    <MicrosoftNETCoreApp21PackageVersion>2.1.0-preview1-26102-01</MicrosoftNETCoreApp21PackageVersion>
     <MicrosoftNETTestSdkPackageVersion>15.3.0</MicrosoftNETTestSdkPackageVersion>
     <MoqPackageVersion>4.7.49</MoqPackageVersion>
     <MsgPackCliPackageVersion>0.9.0-beta2</MsgPackCliPackageVersion>
     <NewtonsoftJsonPackageVersion>10.0.1</NewtonsoftJsonPackageVersion>
     <StackExchangeRedisStrongNamePackageVersion>1.2.4</StackExchangeRedisStrongNamePackageVersion>
-    <SystemBuffersPrimitivesPackageVersion>0.1.0-e171215-1</SystemBuffersPrimitivesPackageVersion>
-    <SystemIOPipelinesExtensionsPackageVersion>0.1.0-e171215-1</SystemIOPipelinesExtensionsPackageVersion>
-    <SystemIOPipelinesPackageVersion>0.1.0-e171215-1</SystemIOPipelinesPackageVersion>
-    <SystemMemoryPackageVersion>4.5.0-preview1-26016-05</SystemMemoryPackageVersion>
-    <SystemNumericsVectorsPackageVersion>4.5.0-preview1-26016-05</SystemNumericsVectorsPackageVersion>
+    <SystemBuffersPrimitivesPackageVersion>0.1.0-e180104-2</SystemBuffersPrimitivesPackageVersion>
+    <SystemIOPipelinesExtensionsPackageVersion>0.1.0-e180104-2</SystemIOPipelinesExtensionsPackageVersion>
+    <SystemIOPipelinesPackageVersion>0.1.0-e180104-2</SystemIOPipelinesPackageVersion>
+    <SystemMemoryPackageVersion>4.5.0-preview1-26102-01</SystemMemoryPackageVersion>
+    <SystemNumericsVectorsPackageVersion>4.5.0-preview1-26102-01</SystemNumericsVectorsPackageVersion>
     <SystemReactiveLinqPackageVersion>3.1.1</SystemReactiveLinqPackageVersion>
     <SystemReflectionEmitPackageVersion>4.3.0</SystemReflectionEmitPackageVersion>
-    <SystemRuntimeCompilerServicesUnsafePackageVersion>4.5.0-preview1-26016-05</SystemRuntimeCompilerServicesUnsafePackageVersion>
-    <SystemThreadingChannelsPackageVersion>4.5.0-preview1-26016-05</SystemThreadingChannelsPackageVersion>
+    <SystemRuntimeCompilerServicesUnsafePackageVersion>4.5.0-preview1-26102-01</SystemRuntimeCompilerServicesUnsafePackageVersion>
+    <SystemThreadingChannelsPackageVersion>4.5.0-preview1-26102-01</SystemThreadingChannelsPackageVersion>
     <SystemThreadingTasksExtensionsPackageVersion>4.5.0-preview2-25707-02</SystemThreadingTasksExtensionsPackageVersion>
     <XunitPackageVersion>2.3.1</XunitPackageVersion>
     <XunitRunnerVisualStudioPackageVersion>2.3.1</XunitRunnerVisualStudioPackageVersion>
diff --git a/src/Microsoft.AspNetCore.Sockets.Client.Http/ServerSentEventsMessageParser.cs b/src/Microsoft.AspNetCore.Sockets.Client.Http/ServerSentEventsMessageParser.cs
index 4ad011babc..08799a5052 100644
--- a/src/Microsoft.AspNetCore.Sockets.Client.Http/ServerSentEventsMessageParser.cs
+++ b/src/Microsoft.AspNetCore.Sockets.Client.Http/ServerSentEventsMessageParser.cs
@@ -2,7 +2,9 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
+using System.Collections.Sequences;
 using System.IO.Pipelines;
 using System.Runtime.CompilerServices;
 using System.Text;
@@ -22,7 +24,7 @@ namespace Microsoft.AspNetCore.Sockets.Internal.Formatters
         private InternalParseState _internalParserState = InternalParseState.ReadMessagePayload;
         private List<byte[]> _data = new List<byte[]>();
 
-        public ParseResult ParseMessage(ReadableBuffer buffer, out ReadCursor consumed, out ReadCursor examined, out byte[] message)
+        public ParseResult ParseMessage(ReadOnlyBuffer buffer, out Position consumed, out Position examined, out byte[] message)
         {
             consumed = buffer.Start;
             examined = buffer.End;
@@ -33,7 +35,7 @@ namespace Microsoft.AspNetCore.Sockets.Internal.Formatters
 
             while (buffer.Length > 0)
             {
-                if (ReadCursorOperations.Seek(start, end, out var lineEnd, ByteLF) == -1)
+                if (ReadOnlyBuffer.Seek(start, end, out var lineEnd, ByteLF) == -1)
                 {
                     // For the case of  data: Foo\r\n\r\<Anytine except \n>
                     if (_internalParserState == InternalParseState.ReadEndOfMessage)
@@ -146,7 +148,7 @@ namespace Microsoft.AspNetCore.Sockets.Internal.Formatters
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private ReadOnlySpan<byte> ConvertBufferToSpan(ReadableBuffer buffer)
+        private ReadOnlySpan<byte> ConvertBufferToSpan(ReadOnlyBuffer buffer)
         {
             if (buffer.IsSingleSpan)
             {
diff --git a/test/Microsoft.AspNetCore.SignalR.Client.Tests/ServerSentEventsParserTests.cs b/test/Microsoft.AspNetCore.SignalR.Client.Tests/ServerSentEventsParserTests.cs
index 4e9d1bfae4..14752323fe 100644
--- a/test/Microsoft.AspNetCore.SignalR.Client.Tests/ServerSentEventsParserTests.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Client.Tests/ServerSentEventsParserTests.cs
@@ -4,6 +4,7 @@
 using System;
 using System.Buffers;
 using System.Collections.Generic;
+using System.Collections.Sequences;
 using System.IO.Pipelines;
 using System.Text;
 using System.Threading.Tasks;
@@ -31,7 +32,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public void ParseSSEMessageSuccessCases(string encodedMessage, string expectedMessage)
         {
             var buffer = Encoding.UTF8.GetBytes(encodedMessage);
-            var readableBuffer = ReadableBuffer.Create(buffer);
+            var readableBuffer = new ReadOnlyBuffer(buffer);
             var parser = new ServerSentEventsMessageParser();
 
             var parseResult = parser.ParseMessage(readableBuffer, out var consumed, out var examined, out var message);
@@ -57,7 +58,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public void ParseSSEMessageFailureCases(string encodedMessage, string expectedExceptionMessage)
         {
             var buffer = Encoding.UTF8.GetBytes(encodedMessage);
-            var readableBuffer = ReadableBuffer.Create(buffer);
+            var readableBuffer = new ReadOnlyBuffer(buffer);
             var parser = new ServerSentEventsMessageParser();
 
             var ex = Assert.Throws<FormatException>(() => { parser.ParseMessage(readableBuffer, out var consumed, out var examined, out var message); });
@@ -85,7 +86,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public void ParseSSEMessageIncompleteParseResult(string encodedMessage)
         {
             var buffer = Encoding.UTF8.GetBytes(encodedMessage);
-            var readableBuffer = ReadableBuffer.Create(buffer);
+            var readableBuffer = new ReadOnlyBuffer(buffer);
             var parser = new ServerSentEventsMessageParser();
 
             var parseResult = parser.ParseMessage(readableBuffer, out var consumed, out var examined, out var message);
@@ -113,7 +114,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 var pipe = new Pipe(new PipeOptions(pool));
 
                 byte[] message = null;
-                ReadCursor consumed = default, examined = default;
+                Position consumed = default, examined = default;
 
                 for (var i = 0; i < messageParts.Length; i++)
                 {
@@ -222,7 +223,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public void ParseMessagesWithMultipleDataLines(string encodedMessage, string expectedMessage)
         {
             var buffer = Encoding.UTF8.GetBytes(encodedMessage);
-            var readableBuffer = ReadableBuffer.Create(buffer);
+            var readableBuffer = new ReadOnlyBuffer(buffer);
             var parser = new ServerSentEventsMessageParser();
 
             var parseResult = parser.ParseMessage(readableBuffer, out var consumed, out var examined, out var message);