diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index 66a3b36ba..04c47720d 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -8,7 +8,8 @@ on:
     branches: [master]
   schedule:
     - cron: '26 22 * * 0'
-
+env:
+  caliburn_sln : "src\\caliburn.micro.sln"
 jobs:
   analyse:
     name: Analyse
@@ -65,10 +66,10 @@ jobs:
       run: dotnet workload list
 
     - name: Restore nuget packages
-      run:  msbuild src\caliburn.micro.sln -t:restore
+      run:  msbuild ${{env.caliburn_sln}}  -t:restore
 
     - name: Build app for release
-      run: msbuild src\caliburn.micro.sln /t:Build 
+      run: msbuild ${{env.caliburn_sln}}  /t:Build 
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
diff --git a/azure-pipeline.yml b/azure-pipeline.yml
index 8c1e348fb..6eac9e207 100644
--- a/azure-pipeline.yml
+++ b/azure-pipeline.yml
@@ -15,7 +15,7 @@ steps:
   displayName: 'Install .NET'
   inputs:
     packageType: 'sdk'
-    version: '8.0.x' 
+    version: '9.0.x' 
 
 
 - task: PowerShell@2
diff --git a/samples/features/Features.NetFive/Features.DotNet.csproj b/samples/features/Features.NetFive/Features.DotNet.csproj
index 0c8c93993..cafeaa540 100644
--- a/samples/features/Features.NetFive/Features.DotNet.csproj
+++ b/samples/features/Features.NetFive/Features.DotNet.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <UseWPF>true</UseWPF>
     <AssemblyName>Features.CrossPlatform</AssemblyName>
     <RootNamespace>Features.CrossPlatform</RootNamespace>
@@ -23,10 +23,10 @@
 
   <ItemGroup>
     <Reference Include="Caliburn.Micro.Core">
-      <HintPath>..\..\..\bin\Caliburn.Micro.Platform\release\net8.0-windows\Caliburn.Micro.Core.dll</HintPath>
+      <HintPath>..\..\..\bin\Caliburn.Micro.Platform\release\net9.0-windows\Caliburn.Micro.Core.dll</HintPath>
     </Reference>
     <Reference Include="Caliburn.Micro.Platform">
-      <HintPath>..\..\..\bin\Caliburn.Micro.Platform\release\net8.0-windows\Caliburn.Micro.Platform.dll</HintPath>
+      <HintPath>..\..\..\bin\Caliburn.Micro.Platform\release\net9.0-windows\Caliburn.Micro.Platform.dll</HintPath>
     </Reference>
   </ItemGroup>
 
diff --git a/samples/setup/Setup.UWP/Setup.UWP.csproj b/samples/setup/Setup.UWP/Setup.UWP.csproj
index b487e2f13..7888d0233 100644
--- a/samples/setup/Setup.UWP/Setup.UWP.csproj
+++ b/samples/setup/Setup.UWP/Setup.UWP.csproj
@@ -127,7 +127,7 @@
       <Version>4.0.173</Version>
     </PackageReference>
     <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform">
-      <Version>6.2.12</Version>
+      <Version>6.2.14</Version>
     </PackageReference>
   </ItemGroup>
   <ItemGroup>
diff --git a/samples/setup/Setup.WPF.Core.VB/Bootstrapper.vb b/samples/setup/Setup.WPF.Core.VB/Bootstrapper.vb
index 5fa1593d3..8f13e1bb0 100644
--- a/samples/setup/Setup.WPF.Core.VB/Bootstrapper.vb
+++ b/samples/setup/Setup.WPF.Core.VB/Bootstrapper.vb
@@ -18,7 +18,7 @@ Public Class Bootstrapper
     End Sub
 
     Protected Overrides Sub OnStartup(sender As Object, e As StartupEventArgs)
-        DisplayRootViewFor(Of ShellViewModel)()
+        DisplayRootViewForAsync(Of ShellViewModel)()
     End Sub
 
     Protected Overrides Function GetInstance(service As Type, key As String) As Object
diff --git a/samples/setup/Setup.WPF.Core.VB/Setup.WPF.Core.VB.vbproj b/samples/setup/Setup.WPF.Core.VB/Setup.WPF.Core.VB.vbproj
index e620206aa..b25bdcff5 100644
--- a/samples/setup/Setup.WPF.Core.VB/Setup.WPF.Core.VB.vbproj
+++ b/samples/setup/Setup.WPF.Core.VB/Setup.WPF.Core.VB.vbproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <RootNamespace>Setup.WPF.Core.VB</RootNamespace>
     <UseWPF>true</UseWPF>
   </PropertyGroup>
@@ -20,7 +20,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Caliburn.Micro" Version="4.0.173" />
+    <PackageReference Include="Caliburn.Micro" Version="4.0.212" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/samples/setup/Setup.WPF.Core/Bootstrapper.cs b/samples/setup/Setup.WPF.Core/Bootstrapper.cs
index 5d1c4b3ce..0b9384619 100644
--- a/samples/setup/Setup.WPF.Core/Bootstrapper.cs
+++ b/samples/setup/Setup.WPF.Core/Bootstrapper.cs
@@ -1,8 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Windows;
 using Caliburn.Micro;
 using Setup.WPF.Core.ViewModels;
@@ -30,7 +27,7 @@ protected override void Configure()
 
         protected override void OnStartup(object sender, StartupEventArgs e)
         {
-            DisplayRootViewFor<ShellViewModel>();
+            DisplayRootViewForAsync<ShellViewModel>();
         }
 
         protected override object GetInstance(Type service, string key)
diff --git a/samples/setup/Setup.WPF.Core/Setup.WPF.Core.csproj b/samples/setup/Setup.WPF.Core/Setup.WPF.Core.csproj
index 8354fadc7..93b91a125 100644
--- a/samples/setup/Setup.WPF.Core/Setup.WPF.Core.csproj
+++ b/samples/setup/Setup.WPF.Core/Setup.WPF.Core.csproj
@@ -2,12 +2,12 @@
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <UseWPF>true</UseWPF>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Caliburn.Micro" Version="4.0.173" />
+    <PackageReference Include="Caliburn.Micro" Version="4.0.212" />
   </ItemGroup>
 
 </Project>
diff --git a/src/Caliburn.Micro.Core.Tests/EventAggregatorTests.cs b/src/Caliburn.Micro.Core.Tests/EventAggregatorTests.cs
index 02f764447..5e501e37d 100644
--- a/src/Caliburn.Micro.Core.Tests/EventAggregatorTests.cs
+++ b/src/Caliburn.Micro.Core.Tests/EventAggregatorTests.cs
@@ -26,12 +26,12 @@ public void A_valid_subscriber_is_assigned_as_a_handler_its_message_type()
         {
             var handlerStub = new Mock<IHandle<object>>().Object;
             var aggregator = new EventAggregator();
-
-            Assert.False(aggregator.HandlerExistsFor(typeof(object)));
+            var messageType = typeof(object);
+            Assert.False(aggregator.HandlerExistsFor(messageType));
 
             aggregator.SubscribeOnPublishedThread(handlerStub);
 
-            Assert.True(aggregator.HandlerExistsFor(typeof(object)));
+            Assert.True(aggregator.HandlerExistsFor(messageType));
         }
     }
 
diff --git a/src/Caliburn.Micro.Core/EventAggregator.cs b/src/Caliburn.Micro.Core/EventAggregator.cs
index 2143c074a..6190b9cba 100644
--- a/src/Caliburn.Micro.Core/EventAggregator.cs
+++ b/src/Caliburn.Micro.Core/EventAggregator.cs
@@ -10,6 +10,8 @@ namespace Caliburn.Micro
     /// <inheritdoc />
     public class EventAggregator : IEventAggregator
     {
+        private static readonly ILog Log = LogManager.GetLog(typeof(EventAggregator));
+
         private readonly List<Handler> _handlers = new List<Handler>();
 
         /// <inheritdoc />
@@ -17,6 +19,8 @@ public virtual bool HandlerExistsFor(Type messageType)
         {
             lock (_handlers)
             {
+                Log.Info("Checking if handler exists for {0}.", messageType.FullName);
+                Log.Info("There are {0} handlers registered.", _handlers.Count);
                 return _handlers.Any(handler => handler.Handles(messageType) && !handler.IsDead);
             }
         }
@@ -38,9 +42,10 @@ public virtual void Subscribe(object subscriber, Func<Func<Task>, Task> marshal)
             {
                 if (_handlers.Any(x => x.Matches(subscriber)))
                 {
+                    Log.Info("Message Handler exists");
                     return;
                 }
-
+                Log.Info("Message Handler Adding it");
                 _handlers.Add(new Handler(subscriber, marshal));
             }
         }
diff --git a/src/Caliburn.Micro.Platform/Caliburn.Micro.Platform.csproj b/src/Caliburn.Micro.Platform/Caliburn.Micro.Platform.csproj
index 5e08e3305..34917cb36 100644
--- a/src/Caliburn.Micro.Platform/Caliburn.Micro.Platform.csproj
+++ b/src/Caliburn.Micro.Platform/Caliburn.Micro.Platform.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="MSBuild.Sdk.Extras">
 
   <PropertyGroup>
-    <TargetFrameworks>net462;uap10.0.19041;net8.0-android;net8.0-ios;net8.0-windows;</TargetFrameworks>
+    <TargetFrameworks>net462;uap10.0.19041;net8.0-android;net8.0-ios;net9.0-android;net9.0-ios;net8.0-windows;net9.0-windows</TargetFrameworks>
     <PackageId>Caliburn.Micro</PackageId>
     <Product>Caliburn.Micro</Product>
     <RootNamespace>Caliburn.Micro</RootNamespace>
@@ -52,6 +52,10 @@
     <PackageReference Include="Microsoft.Xaml.Behaviors.Wpf" Version="1.1.135" />
     <Compile Include="Platforms\net46-netcore\**\*.cs" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'net9.0-windows'">
+    <PackageReference Include="Microsoft.Xaml.Behaviors.Wpf" Version="1.1.135" />
+    <Compile Include="Platforms\net46-netcore\**\*.cs" />
+  </ItemGroup>
 
   <ItemGroup Label="Package">
     <None Include="..\..\CaliburnIcon.png">
@@ -79,6 +83,18 @@
     <Compile Include="ViewModelLocator.cs" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'net9.0-android'">
+    <Compile Remove="*.cs" />
+    <Compile Include="Platforms\android\**\*.cs" />
+    <Compile Include="ViewModelLocator.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'net9.0-ios'">
+    <Compile Remove="*.cs" />
+    <Compile Include="Platforms\ios\**\*.cs" />
+    <Compile Include="ViewModelLocator.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Update="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageReference Update="Nerdbank.GitVersioning" Version="3.6.146" />
diff --git a/src/global.json b/src/global.json
index 0a13e1705..18141da90 100644
--- a/src/global.json
+++ b/src/global.json
@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.x",
+    "version": "9.0.x",
     "rollForward": "latestFeature"
   },
   "msbuild-sdks": {