diff --git a/functions.php b/functions.php
index 1d8f4a8..b7e5ffb 100644
--- a/functions.php
+++ b/functions.php
@@ -153,7 +153,7 @@ function radiate_scripts() {
 	// Add Genericons, used in the main stylesheet.
 	wp_enqueue_style( 'radiate-genericons', get_template_directory_uri() . '/genericons/genericons.css', array(), '3.3.1' );
 
-	wp_enqueue_script( 'radiate-navigation', get_template_directory_uri() . '/js/navigation.js', array(), '20120206', true );
+	wp_enqueue_script( 'radiate-navigation', get_template_directory_uri() . '/js/navigation.js', array(), '20260930', true );
 
 	wp_enqueue_script( 'radiate-skip-link-focus-fix', get_template_directory_uri() . '/js/skip-link-focus-fix.js', array(), '20130115', true );
 
diff --git a/js/navigation.js b/js/navigation.js
index d276f4a..5b773bd 100644
--- a/js/navigation.js
+++ b/js/navigation.js
@@ -81,6 +81,10 @@ jQuery(document).ready(function() {
     var container;
     container = document.getElementById( 'site-navigation' );
 
+    if ( ! container ) {
+        return;
+    }
+
     /**
      * Toggles `focus` class to allow submenu access on tablets.
      */
diff --git a/tests/e2e/specs/mobile-menu/navigation-missing-container.spec.ts b/tests/e2e/specs/mobile-menu/navigation-missing-container.spec.ts
new file mode 100644
index 0000000..a629e1b
--- /dev/null
+++ b/tests/e2e/specs/mobile-menu/navigation-missing-container.spec.ts
@@ -0,0 +1,34 @@
+import { test, expect } from "../../fixtures";
+
+/**
+ * @area mobile-menu
+ * @tier fresh
+ * @guards themegrill/radiate-pro#28
+ * @source fix/28-navigation-guard 2026-09-30; js/navigation.js
+ * @why The touch-submenu handler in navigation.js read #site-navigation
+ *      without a null check (the first handler already had one), so any page
+ *      without that element (a child theme whose header.php drops the nav)
+ *      threw "Cannot read properties of null (reading 'querySelectorAll')".
+ *      Removes the <nav> while the page loads to reproduce that header, and
+ *      asserts the page raises no script error.
+ */
+test("navigation.js raises no error when #site-navigation is missing @fresh @mobile-menu", async ({
+  page,
+}) => {
+  // Drop the <nav> as the parser adds it, so it is gone before the footer scripts run.
+  await page.addInitScript(() => {
+    new MutationObserver(() =>
+      document.getElementById("site-navigation")?.remove(),
+    ).observe(document, { childList: true, subtree: true });
+  });
+
+  const errors: string[] = [];
+  page.on("pageerror", (e) => errors.push(e.message));
+
+  await page.goto("/");
+  await page.waitForLoadState("networkidle");
+
+  await expect(page.locator("#site-navigation")).toHaveCount(0);
+  await expect(page.locator("script[src*='navigation']")).toHaveCount(1);
+  expect(errors, "script errors").toEqual([]);
+});