diff --git a/browser/base/content/webext-panels.js b/browser/base/content/webext-panels.js
index b09747bf92f1..9361e3972cd4 100644
--- a/browser/base/content/webext-panels.js
+++ b/browser/base/content/webext-panels.js
@@ -70,6 +70,33 @@ function getBrowser(panel) {
 
   stack.appendChild(browser);
 
+  browser.addEventListener(
+    "DoZoomEnlargeBy10",
+    () => {
+      let { ZoomManager } = browser.ownerGlobal;
+      let zoom = browser.fullZoom;
+      zoom += 0.1;
+      if (zoom > ZoomManager.MAX) {
+        zoom = ZoomManager.MAX;
+      }
+      browser.fullZoom = zoom;
+    },
+    true
+  );
+  browser.addEventListener(
+    "DoZoomReduceBy10",
+    () => {
+      let { ZoomManager } = browser.ownerGlobal;
+      let zoom = browser.fullZoom;
+      zoom -= 0.1;
+      if (zoom < ZoomManager.MIN) {
+        zoom = ZoomManager.MIN;
+      }
+      browser.fullZoom = zoom;
+    },
+    true
+  );
+
   return readyPromise.then(() => {
     ExtensionParent.apiManager.emit(
       "extension-browser-inserted",
diff --git a/browser/components/customizableui/PanelMultiView.jsm b/browser/components/customizableui/PanelMultiView.jsm
index 556d260a86da..996b63330021 100644
--- a/browser/components/customizableui/PanelMultiView.jsm
+++ b/browser/components/customizableui/PanelMultiView.jsm
@@ -338,7 +338,7 @@ var PanelMultiView = class extends AssociatedToNode {
 
     return (
       doc.getElementById(id) ||
-      viewCacheTemplate.content.querySelector("#" + id)
+      viewCacheTemplate?.content.querySelector("#" + id)
     );
   }
 
diff --git a/browser/modules/ZoomUI.jsm b/browser/modules/ZoomUI.jsm
index 3c84a654110b..d3eafe2ac717 100644
--- a/browser/modules/ZoomUI.jsm
+++ b/browser/modules/ZoomUI.jsm
@@ -133,6 +133,12 @@ async function updateZoomUI(aBrowser, aAnimate = false) {
     win.document,
     "appMenu-zoomReset-button"
   );
+
+  // Exit early if UI elements aren't present.
+  if (!appMenuZoomReset) {
+    return;
+  }
+
   let customizableZoomControls = win.document.getElementById("zoom-controls");
   let customizableZoomReset = win.document.getElementById("zoom-reset-button");
   let urlbarZoomButton = win.document.getElementById("urlbar-zoom-button");