diff --git a/src/main/java/info/istlab/ServerTester/App.java b/src/main/java/info/istlab/ServerTester/App.java
index ec5107a..85958d7 100644
--- a/src/main/java/info/istlab/ServerTester/App.java
+++ b/src/main/java/info/istlab/ServerTester/App.java
@@ -21,6 +21,14 @@
     }
 
     public static void main(String[] args) {
+        Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
+            @Override
+            public void uncaughtException(Thread t, Throwable e) {
+                // 例外をログに書き出したり、無視したりできます
+                // System.err.println("Uncaught exception: " + e.getMessage());
+            }
+        });
+
         Class<?> clazz = App.class; // Mainクラスを指定
         String location = clazz.getProtectionDomain().getCodeSource().getLocation().getPath();
         isJAR = location.endsWith(".jar");
diff --git a/src/main/java/info/istlab/ServerTester/Host.java b/src/main/java/info/istlab/ServerTester/Host.java
index 23233d1..23cc9e0 100644
--- a/src/main/java/info/istlab/ServerTester/Host.java
+++ b/src/main/java/info/istlab/ServerTester/Host.java
@@ -38,11 +38,8 @@
         add(addPanel, BorderLayout.NORTH);
         mainhost = this;
         // udpServer = new UDPServer();
-        SwingUtilities.invokeLater(new Runnable() {
-            @Override
-            public void run() {
-                setVisible(true);
-            }
+        SwingUtilities.invokeLater(() -> {
+            setVisible(true);
         });
     }
 
diff --git a/src/main/java/info/istlab/ServerTester/JTAConsole.java b/src/main/java/info/istlab/ServerTester/JTAConsole.java
index eaf2e05..d8e4f44 100644
--- a/src/main/java/info/istlab/ServerTester/JTAConsole.java
+++ b/src/main/java/info/istlab/ServerTester/JTAConsole.java
@@ -163,7 +163,9 @@
         // if (!process.isAlive()) {
         //     // Launcher.allProcs.remove(process);
         // }
-        frame.setVisible(false);
+        SwingUtilities.invokeLater(() -> {
+            frame.setVisible(false);
+        });
     }
 
     @Override
diff --git a/src/main/java/info/istlab/ServerTester/MulticastReceiver.java b/src/main/java/info/istlab/ServerTester/MulticastReceiver.java
index 175ac26..91e1a21 100644
--- a/src/main/java/info/istlab/ServerTester/MulticastReceiver.java
+++ b/src/main/java/info/istlab/ServerTester/MulticastReceiver.java
@@ -9,6 +9,8 @@
 import java.nio.channels.DatagramChannel;
 import java.util.Hashtable;
 
+import javax.swing.SwingUtilities;
+
 public class MulticastReceiver implements Runnable {
     Thread thread;
     // MulticastSocket socket;
@@ -90,7 +92,9 @@
         if (remoteHostsWindow != null) {
             remoteHostsWindow.autoPack = true;
             remoteHostsWindow.packIfNotResized();
-            remoteHostsWindow.frame.setVisible(true);
+            SwingUtilities.invokeLater(() -> {
+                remoteHostsWindow.frame.setVisible(true);
+            });
         } else {
             remoteHostsWindow = new RemoteHostsWindow(receivedData);
         }
diff --git a/src/main/java/info/istlab/ServerTester/RemoteHostsWindow.java b/src/main/java/info/istlab/ServerTester/RemoteHostsWindow.java
index ee36785..95554c1 100644
--- a/src/main/java/info/istlab/ServerTester/RemoteHostsWindow.java
+++ b/src/main/java/info/istlab/ServerTester/RemoteHostsWindow.java
@@ -15,6 +15,7 @@
 import javax.swing.JLabel;
 import javax.swing.JPanel;
 import javax.swing.JTabbedPane;
+import javax.swing.SwingUtilities;
 
 public class RemoteHostsWindow extends JPanel implements Runnable{
     JTabbedPane tabbedPane;
@@ -85,7 +86,9 @@
         }
         frame.pack();
         frame.setLocation(Host.mainhost.nextTo(10,10));
-        frame.setVisible(true);
+        SwingUtilities.invokeLater(() -> {
+            frame.setVisible(true);
+        });
     }
 }
 
diff --git a/src/main/java/info/istlab/ServerTester/Server.java b/src/main/java/info/istlab/ServerTester/Server.java
index 3e995c3..f12c99d 100644
--- a/src/main/java/info/istlab/ServerTester/Server.java
+++ b/src/main/java/info/istlab/ServerTester/Server.java
@@ -98,6 +98,12 @@
     }
 
     public String getBindAddress() {
+        if (serverSocket == null) {
+            return "/null";
+        }
+        if (serverSocket.getInetAddress() == null) {
+            return "/null";
+        }
         return serverSocket.getInetAddress().toString();
     }
 
diff --git a/src/main/java/info/istlab/ServerTester/ServerPanel.java b/src/main/java/info/istlab/ServerTester/ServerPanel.java
index 3dc2d3b..e9e1e8c 100644
--- a/src/main/java/info/istlab/ServerTester/ServerPanel.java
+++ b/src/main/java/info/istlab/ServerTester/ServerPanel.java
@@ -64,7 +64,7 @@
         });
 
         delButton = new JButton("Delete");
-        delButton.setEnabled(false);
+        delButton.setEnabled(true);
         delButton.addActionListener(e -> {
             server.close();
             Host.mainhost.mainPanel.remove(this);
diff --git a/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java b/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java
index fd14885..863f3e4 100644
--- a/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java
+++ b/src/main/java/info/istlab/ServerTester/WhiteBoardClient.java
@@ -18,6 +18,7 @@
 
 import javax.swing.JFrame;
 import javax.swing.JPanel;
+import javax.swing.SwingUtilities;
 
 public class WhiteBoardClient extends JPanel implements MouseListener, MouseMotionListener, Runnable {
     private static final long serialVersionUID = 1L;
@@ -51,7 +52,9 @@
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setSize(600, 400);
         frame.add(this);
-        frame.setVisible(true);
+        SwingUtilities.invokeLater(() -> {
+            frame.setVisible(true);
+        });
 
         System.out.println("Client socket info: " + socket.toString());