From 10558b2682dcbf254c4880942b61cb2c611b60ac Mon Sep 17 00:00:00 2001
From: Michael Jumper <mjumper@apache.org>
Date: Thu, 11 Dec 2025 22:39:46 -0800
Subject: [PATCH] GUACAMOLE-2181: Avoid NPE if servlet container is shut down
 before extensions are loaded.

---
 .../GuacamoleServletContextListener.java         | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/guacamole/src/main/java/org/apache/guacamole/GuacamoleServletContextListener.java b/guacamole/src/main/java/org/apache/guacamole/GuacamoleServletContextListener.java
index aef48592a..99db0b9fd 100644
--- a/guacamole/src/main/java/org/apache/guacamole/GuacamoleServletContextListener.java
+++ b/guacamole/src/main/java/org/apache/guacamole/GuacamoleServletContextListener.java
@@ -297,13 +297,15 @@ public class GuacamoleServletContextListener extends GuiceServletContextListener
             }
 
             // Inform any listeners that application shutdown has completed
-            try {
-                listenerService.handleEvent(new ApplicationShutdownEvent() {
-                    // The application shutdown event currently has no content
-                });
-            }
-            catch (GuacamoleException e) {
-                logger.error("An extension listening for application shutdown failed: {}", e.getMessage(), e);
+            if (listenerService != null) {
+                try {
+                    listenerService.handleEvent(new ApplicationShutdownEvent() {
+                        // The application shutdown event currently has no content
+                    });
+                }
+                catch (GuacamoleException e) {
+                    logger.error("An extension listening for application shutdown failed: {}", e.getMessage(), e);
+                }
             }
 
         }