diff --git a/framework-dotnet/src/lib/MBS.Core/Application.cs b/framework-dotnet/src/lib/MBS.Core/Application.cs
index 024c65c..2a84844 100644
--- a/framework-dotnet/src/lib/MBS.Core/Application.cs
+++ b/framework-dotnet/src/lib/MBS.Core/Application.cs
@@ -1,4 +1,6 @@
-namespace MBS.Core;
+using System.ComponentModel;
+
+namespace MBS.Core;
 
 public class Application
 {
@@ -25,9 +27,21 @@ public class Application
 		return e.ExitCode;
 	}
 
+	public event EventHandler<CancelEventArgs> BeforeStartInternal;
+	protected virtual void OnBeforeStartInternal(CancelEventArgs e)
+	{
+		BeforeStartInternal?.Invoke(this, e);
+	}
+
 	public int Start()
 	{
 		Instance = this;
+
+		CancelEventArgs e = new CancelEventArgs();
+		OnBeforeStartInternal(e);
+		if (e.Cancel)
+			return 2;
+
 		int exitCode = StartInternal();
 		
 		Instance = null;