diff --git a/src/Directory.Build.props b/src/Directory.Build.props
index 682ceac121..c159990977 100644
--- a/src/Directory.Build.props
+++ b/src/Directory.Build.props
@@ -13,14 +13,16 @@
     <!-- VB specific settings -->
     <When Condition="'$(Language)' == 'VB'">
       <PropertyGroup>
-        <LangVersion>15.5</LangVersion>
+        <LangVersion>16</LangVersion>
       </PropertyGroup>
     </When>
 
     <!-- C# specific settings -->
     <When Condition="'$(Language)' == 'C#'">
       <PropertyGroup>
-        <LangVersion>8.0</LangVersion>
+        <LangVersion>preview</LangVersion>
+        <WarningLevel>9999</WarningLevel>
+        <Nullable>enable</Nullable>
       </PropertyGroup>
     </When>
   </Choose>
diff --git a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKAnalyzerTemplateWizard.cs b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKAnalyzerTemplateWizard.cs
index eb1a6acd6c..b0a5791a52 100644
--- a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKAnalyzerTemplateWizard.cs
+++ b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKAnalyzerTemplateWizard.cs
@@ -4,7 +4,7 @@
 
 public class RoslynSDKAnalyzerTemplateWizard : RoslynSDKChildTemplateWizard
 {
-    public static Project Project { get; private set; }
+    public static Project? Project { get; private set; }
 
     public override void OnProjectFinishedGenerating(Project project)
     {
diff --git a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKChildTemplateWizard.InterfaceMembers.cs b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKChildTemplateWizard.InterfaceMembers.cs
index 0d4a299e71..8d6ba5d8f0 100644
--- a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKChildTemplateWizard.InterfaceMembers.cs
+++ b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKChildTemplateWizard.InterfaceMembers.cs
@@ -18,7 +18,9 @@ public void ProjectItemFinishedGenerating(ProjectItem projectItem) { }
     public void RunStarted(object automationObject, Dictionary<string, string> replacementsDictionary, WizardRunKind runKind, object[] customParams)
     {
         ThreadHelper.ThrowIfNotOnUIThread();
-
-        OnRunStarted(automationObject as DTE, replacementsDictionary, runKind, customParams);
+        if (automationObject is DTE dte)
+        {
+            OnRunStarted(dte, replacementsDictionary, runKind, customParams);
+        }
     }
 }
diff --git a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKCodeFixTemplateWizard.cs b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKCodeFixTemplateWizard.cs
index e46896a572..f19a27dea0 100644
--- a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKCodeFixTemplateWizard.cs
+++ b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKCodeFixTemplateWizard.cs
@@ -6,7 +6,7 @@
 
 public class RoslynSDKCodeFixTemplateWizard : RoslynSDKChildTemplateWizard
 {
-    public static Project Project { get; private set; }
+    public static Project? Project { get; private set; }
 
     public override void OnProjectFinishedGenerating(Project project)
     {
diff --git a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKRootTemplateWizard.InterfaceMembers.cs b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKRootTemplateWizard.InterfaceMembers.cs
index 51e48abb4a..d6559c2fda 100644
--- a/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKRootTemplateWizard.InterfaceMembers.cs
+++ b/src/VisualStudio.Roslyn.SDK/Roslyn.SDK.Template.Wizard/RoslynSDKRootTemplateWizard.InterfaceMembers.cs
@@ -16,6 +16,9 @@ public void RunStarted(object automationObject, Dictionary<string, string> repla
     {
         ThreadHelper.ThrowIfNotOnUIThread();
 
-        OnRunStarted(automationObject as DTE, replacementsDictionary, runKind, customParams);
+        if (automationObject is DTE dte)
+        {
+            OnRunStarted(dte, replacementsDictionary, runKind, customParams);
+        }
     }
 }
diff --git a/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Control/Roslyn.SyntaxVisualizer.Control.csproj b/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Control/Roslyn.SyntaxVisualizer.Control.csproj
index 354a8a12bb..f6261fa079 100644
--- a/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Control/Roslyn.SyntaxVisualizer.Control.csproj
+++ b/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Control/Roslyn.SyntaxVisualizer.Control.csproj
@@ -7,8 +7,6 @@
     <IsProductComponent>false</IsProductComponent>
     <UseWpf>true</UseWpf>
     <UseWindowsForms>true</UseWindowsForms>
-    <Nullable>enable</Nullable>
-    <LangVersion>9</LangVersion>
   </PropertyGroup>
 
   <!-- Package References -->
diff --git a/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Extension/Roslyn.SyntaxVisualizer.Extension.csproj b/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Extension/Roslyn.SyntaxVisualizer.Extension.csproj
index 29453ba95c..03f01cead1 100644
--- a/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Extension/Roslyn.SyntaxVisualizer.Extension.csproj
+++ b/src/VisualStudio.Roslyn.SDK/SyntaxVisualizer/Roslyn.SyntaxVisualizer.Extension/Roslyn.SyntaxVisualizer.Extension.csproj
@@ -7,8 +7,6 @@
     <EnableDefaultEmbeddedResourceItems>false</EnableDefaultEmbeddedResourceItems>
     <IsProductComponent>false</IsProductComponent>
     <UseWpf>true</UseWpf>
-    <Nullable>enable</Nullable>
-    <LangVersion>9</LangVersion>
 
     <!-- VSIX -->
     <CreateVsixContainer>false</CreateVsixContainer>