diff --git a/src/common/mainWorldContentScriptBridge/Server.js b/src/common/mainWorldContentScriptBridge/Server.js
index 321a068..cf19e4d 100644
--- a/src/common/mainWorldContentScriptBridge/Server.js
+++ b/src/common/mainWorldContentScriptBridge/Server.js
@@ -21,6 +21,14 @@
     if (e.source !== window || e.data?.target !== this.CSTarget || !uuid)
       return;
 
+    // If chrome.runtime.id is undefined, then this content script belongs to a
+    // dead extension (see https://stackoverflow.com/a/69603416).
+    if (typeof chrome.runtime.id === 'undefined') {
+      console.debug(
+          '[MainWorldContentScriptBridgeServer] Not handling message because this is a dead server.');
+      return;
+    }
+
     const action = e.data?.action;
     const request = e.data?.request;
     return this.handler(uuid, action, request);