diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..3056bfa
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,11 @@
+; Visual Studio Extension : http://visualstudiogallery.msdn.microsoft.com/c8bccfe2-650c-4b42-bc5c-845e21f96328
+; See http://editorconfig.org/ for more informations
+; Top-most EditorConfig file
+root = false
+
+# Additions for AppVeyor tests, use Git Extensions settings by default
+
+[*.cs]
+# WFO1000: A property should determine its property content serialization with the DesignerSerializationVisibilityAttribute, DefaultValueAttribute or the ShouldSerializeProperty method
+# Silent for now, see https://github.com/dotnet/winforms/issues/12476
+dotnet_diagnostic.WFO1000.severity = silent
diff --git a/Directory.Build.props b/Directory.Build.props
index 6bb10ae..fd73717 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -2,7 +2,7 @@
 <Project>
 
   <PropertyGroup>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <UseWindowsForms>true</UseWindowsForms>
     <DeterministicSourcePaths Condition="'$(EnableSourceLink)' == ''">false</DeterministicSourcePaths>
   </PropertyGroup>
diff --git a/ICSharpCode.TextEditor.Sample/ICSharpCode.TextEditor.Sample.csproj b/ICSharpCode.TextEditor.Sample/ICSharpCode.TextEditor.Sample.csproj
index b0566a5..3a9c624 100644
--- a/ICSharpCode.TextEditor.Sample/ICSharpCode.TextEditor.Sample.csproj
+++ b/ICSharpCode.TextEditor.Sample/ICSharpCode.TextEditor.Sample.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <UseWindowsForms>true</UseWindowsForms>
   </PropertyGroup>
 
diff --git a/Project/ICSharpCode.TextEditor.csproj b/Project/ICSharpCode.TextEditor.csproj
index a00b36b..b50b16c 100644
--- a/Project/ICSharpCode.TextEditor.csproj
+++ b/Project/ICSharpCode.TextEditor.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Library</OutputType>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <UseWindowsForms>true</UseWindowsForms>
     <DeterministicSourcePaths Condition="'$(EnableSourceLink)' == ''">false</DeterministicSourcePaths>
     <SuppressNETCoreSdkPreviewMessage>true</SuppressNETCoreSdkPreviewMessage>
diff --git a/Test/ICSharpCode.TextEditor.Tests.csproj b/Test/ICSharpCode.TextEditor.Tests.csproj
index c8423b3..5ec99f3 100644
--- a/Test/ICSharpCode.TextEditor.Tests.csproj
+++ b/Test/ICSharpCode.TextEditor.Tests.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <OutputType>Library</OutputType>
     <OutputPath>..\..\..\..\bin\UnitTests</OutputPath>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <UseWindowsForms>true</UseWindowsForms>
   </PropertyGroup>