diff --git a/ci/ci.yml b/ci/ci.yml
index a5a1f25..31345f4 100644
--- a/ci/ci.yml
+++ b/ci/ci.yml
@@ -23,7 +23,8 @@ variables:
 
 jobs:
 - job: Windows
-  pool: 'Hosted VS2017'
+  pool:
+    vmImage: 'windows-2019'
   steps:
   - template: steps-build-core.yml
   - template: steps-build-samples.yml
diff --git a/ci/signed.yml b/ci/signed.yml
index 82ec9bf..70e93a8 100644
--- a/ci/signed.yml
+++ b/ci/signed.yml
@@ -15,7 +15,8 @@ variables:
 
 jobs:
 - job: Windows
-  pool: 'Hosted VS2017'
+  pool:
+    vmImage: 'windows-2019'
   steps:
   - template: steps-build-core.yml
   - template: steps-build-samples.yml
diff --git a/ci/steps-build-core.yml b/ci/steps-build-core.yml
index 0c48aaa..c9217c6 100644
--- a/ci/steps-build-core.yml
+++ b/ci/steps-build-core.yml
@@ -4,9 +4,9 @@
 
 steps:
 - task: DotNetCoreInstaller@1
-  displayName: 'Install .NET Core SDK 3.1.300'
+  displayName: 'Install .NET Core SDK 6.0.201'
   inputs:
-    version: 3.1.100
+    version: 6.0.201
 
 - task: DotNetCoreCLI@2
   displayName: "Build and run unit tests on Core library"
diff --git a/ci/steps-build-samples.yml b/ci/steps-build-samples.yml
index 31a856e..00fd558 100644
--- a/ci/steps-build-samples.yml
+++ b/ci/steps-build-samples.yml
@@ -7,7 +7,7 @@ steps:
   displayName: 'Create conda environment for hosting Jupyter kernels'
   inputs:
     environmentName: core_tests
-    packageSpecs: python=3.6 notebook jupyter_client pytest nose pip>=18.1
+    packageSpecs: python=3.7 notebook jupyter_client pytest nose pip>=18.1
 
 - script: |
      echo $PATH
diff --git a/examples/echo-kernel/echo-kernel.csproj b/examples/echo-kernel/echo-kernel.csproj
index a772213..6eabbc2 100644
--- a/examples/echo-kernel/echo-kernel.csproj
+++ b/examples/echo-kernel/echo-kernel.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <PackAsTool>True</PackAsTool>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
 
     <!--
       NB: We need for the tool command name to match the pattern dotnet-*,
diff --git a/examples/moon-kernel/moon-kernel.csproj b/examples/moon-kernel/moon-kernel.csproj
index 7b102d0..6009a54 100644
--- a/examples/moon-kernel/moon-kernel.csproj
+++ b/examples/moon-kernel/moon-kernel.csproj
@@ -4,7 +4,7 @@
     <ToolCommandName>dotnet-imoon</ToolCommandName>
     <PackAsTool>True</PackAsTool>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <Version>1.0</Version>
   </PropertyGroup>
 
diff --git a/src/Data/Protocol.cs b/src/Data/Protocol.cs
index 68c3d74..0874d5a 100644
--- a/src/Data/Protocol.cs
+++ b/src/Data/Protocol.cs
@@ -62,7 +62,7 @@ public class Message
         public MessageHeader ParentHeader { get; set; }
 
         // FIXME: make not just an object.
-        public object Metadata { get; set; }
+        public object Metadata { get; set; } = new Dictionary<string, object>();
 
         // FIXME: make not just an object.
         public MessageContent Content { get; set; }
@@ -87,6 +87,11 @@ public Message AsReplyTo(Message parent)
 
     }
 
+    public interface IHasStatus<TStatus>
+    {
+        public TStatus Status { get; set; }
+    }
+
     [JsonObject(MemberSerialization.OptIn)]
     public class MessageContent
     {
@@ -129,8 +134,11 @@ public Dictionary<string, object> Data
     }
 
     [JsonObject(MemberSerialization.OptIn)]
-    public class KernelInfoReplyContent : MessageContent
+    public class KernelInfoReplyContent : MessageContent, IHasStatus<ExecuteStatus>
     {
+        [JsonProperty("status")]
+        public ExecuteStatus Status { get; set; } = ExecuteStatus.Ok;
+
         [JsonProperty("protocol_version")]
         public string ProtocolVersion { get => "5.2.0"; }
 
@@ -215,10 +223,25 @@ public class ExecuteInputContent : MessageContent
     }
 
     [JsonObject(MemberSerialization.OptIn)]
-    public class ExecuteReplyContent : MessageContent
+    public class ExecuteReplyContent : MessageContent, IHasStatus<ExecuteStatus>
     {
         [JsonProperty("status")]
-        public ExecuteStatus ExecuteStatus { get; set; }
+        public ExecuteStatus Status { get; set; }
+
+        // For backwards compatability, also define ExecuteStatus as forwarding
+        // to status.
+        [Obsolete("Please use Status.")]
+        public ExecuteStatus ExecuteStatus
+        {
+            get
+            {
+                return Status;
+            }
+            set
+            {
+                Status = value;
+            }
+        }
 
         [JsonProperty("execution_count")]
         public int? ExecutionCount { get; set; }
@@ -232,10 +255,26 @@ public class ExecuteReplyContent : MessageContent
     }
 
     [JsonObject(MemberSerialization.OptIn)]
-    public class CompleteReplyContent : MessageContent
+    public class CompleteReplyContent : MessageContent, IHasStatus<CompleteStatus>
     {
         [JsonProperty("status")]
-        public CompleteStatus CompleteStatus { get; set; }
+        public CompleteStatus Status { get; set; }
+
+
+        // For backwards compatability, also define ExecuteStatus as forwarding
+        // to status.
+        [Obsolete("Please use Status.")]
+        public CompleteStatus CompleteStatus
+        {
+            get
+            {
+                return Status;
+            }
+            set
+            {
+                Status = value;
+            }
+        }
 
         [JsonProperty("matches")]
         public List<string> Matches { get; set; } = new List<string>();
diff --git a/src/Engines/CompletionResult.cs b/src/Engines/CompletionResult.cs
index 7ce7b12..6889194 100644
--- a/src/Engines/CompletionResult.cs
+++ b/src/Engines/CompletionResult.cs
@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+#nullable enable
+
 using System;
 using System.Collections;
 using System.Collections.Generic;
diff --git a/src/Extensions/Messages.cs b/src/Extensions/Messages.cs
index 0496faf..c0fb137 100644
--- a/src/Extensions/Messages.cs
+++ b/src/Extensions/Messages.cs
@@ -118,7 +118,9 @@ public static void SendMessage(this IOutgoingSocket socket, KernelContext contex
                 {
                     message.Header,
                     message.ParentHeader,
-                    message.Metadata,
+                    // Make sure that metadata is never null when going out
+                    // over the wire.
+                    message.Metadata ?? new Dictionary<string, object>(),
                     message.Content
                 }
                 .Select(frame => JsonConvert.SerializeObject(frame))
diff --git a/src/jupyter-core.csproj b/src/jupyter-core.csproj
index c860ff1..8fe1360 100644
--- a/src/jupyter-core.csproj
+++ b/src/jupyter-core.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <OutputType>Library</OutputType>
     <TargetFramework>netstandard2.1</TargetFramework>
-    <LangVersion>8.0</LangVersion>
+    <LangVersion>10.0</LangVersion>
 
     <AssemblyName>Microsoft.Jupyter.Core</AssemblyName>
     <Version Condition=" '$(BUILD_MAJOR)' != ''  ">$(BUILD_MAJOR).$(BUILD_MINOR).0.0</Version>
@@ -31,7 +31,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="3.0.0" />
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="4.5.0" />
     <PackageReference Include="NetMQ" Version="4.0.0.1" />
-    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
     <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
 
     <PackageReference Include="System.Net.Security" Version="4.3.1" />
diff --git a/tests/core/InputParserTests.cs b/tests/core/InputParserTests.cs
index ce29b7a..34c7d12 100644
--- a/tests/core/InputParserTests.cs
+++ b/tests/core/InputParserTests.cs
@@ -9,12 +9,7 @@
 
 namespace Microsoft.Jupyter.Core
 {
-    internal class MundaneSymbol : ISymbol
-    {
-        public string Name { get; set; }
-        
-        public SymbolKind Kind { get; set; }
-    }
+    internal record MundaneSymbol(string Name, SymbolKind Kind) : ISymbol;
 
     internal class MockSymbolResolver : ISymbolResolver
     {
@@ -32,13 +27,8 @@ internal class MockSymbolResolver : ISymbolResolver
                 } as ISymbol
             : 
             this.otherSymbols.Contains(symbolName)
-            ? new MundaneSymbol
-                {
-                    Name = symbolName,
-                    Kind = SymbolKind.Callable
-                } as ISymbol
-            :
-            null;
+            ? new MundaneSymbol(symbolName, SymbolKind.Callable) as ISymbol
+            : null;
     }
 
     [TestClass]
diff --git a/tests/core/core.csproj b/tests/core/core.csproj
index 4679090..56a0572 100644
--- a/tests/core/core.csproj
+++ b/tests/core/core.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
 
     <IsPackable>false</IsPackable>
     <IsTestProject>true</IsTestProject>