diff --git a/browser_patches/firefox/BUILD_NUMBER b/browser_patches/firefox/BUILD_NUMBER
index 1630fd5c04..12fc4b2a28 100644
--- a/browser_patches/firefox/BUILD_NUMBER
+++ b/browser_patches/firefox/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1177
-Changed: lushnikov@chromium.org Wed Sep 30 03:11:29 MDT 2020
+1178
+Changed: lushnikov@chromium.org Wed Sep 30 23:36:27 PDT 2020
diff --git a/browser_patches/firefox/juggler/TargetRegistry.js b/browser_patches/firefox/juggler/TargetRegistry.js
index 2f6a80aca0..d3ebab6f89 100644
--- a/browser_patches/firefox/juggler/TargetRegistry.js
+++ b/browser_patches/firefox/juggler/TargetRegistry.js
@@ -147,8 +147,8 @@ class TargetRegistry {
 
         const sessions = [];
         const readyData = { sessions, target };
-        this.emit(TargetRegistry.Events.TargetCreated, readyData);
         target.markAsReported();
+        this.emit(TargetRegistry.Events.TargetCreated, readyData);
         return {
           scriptsToEvaluateOnNewDocument: target.browserContext().scriptsToEvaluateOnNewDocument,
           bindings: target.browserContext().bindings,
@@ -321,8 +321,8 @@ class TargetRegistry {
     return target.id();
   }
 
-  targets() {
-    return Array.from(this._browserToTarget.values());
+  reportedTargets() {
+    return Array.from(this._browserToTarget.values()).filter(pageTarget => pageTarget._isReported);
   }
 
   targetForBrowser(browser) {
@@ -364,6 +364,7 @@ class PageTarget {
       helper.addProgressListener(tab.linkedBrowser, navigationListener, Ci.nsIWebProgress.NOTIFY_LOCATION),
     ];
 
+    this._isReported = false;
     this._reportedPromise = new Promise(resolve => {
       this._reportedCallback = resolve;
     });
@@ -379,6 +380,7 @@ class PageTarget {
   }
 
   markAsReported() {
+    this._isReported = true;
     this._reportedCallback();
   }
 
@@ -491,7 +493,8 @@ class PageTarget {
     this._registry._browserToTarget.delete(this._linkedBrowser);
     this._registry._browserBrowsingContextToTarget.delete(this._linkedBrowser.browsingContext);
     helper.removeListeners(this._eventListeners);
-    this._registry.emit(TargetRegistry.Events.TargetDestroyed, this);
+    if (this._isReported)
+      this._registry.emit(TargetRegistry.Events.TargetDestroyed, this);
   }
 }
 
diff --git a/browser_patches/firefox/juggler/content/main.js b/browser_patches/firefox/juggler/content/main.js
index b1f1231403..184096981b 100644
--- a/browser_patches/firefox/juggler/content/main.js
+++ b/browser_patches/firefox/juggler/content/main.js
@@ -90,10 +90,11 @@ const applySetting = {
 };
 
 function initialize() {
-  const loadContext = docShell.QueryInterface(Ci.nsILoadContext);
-  const userContextId = loadContext.originAttributes.userContextId;
-
-  const response = sendSyncMessage('juggler:content-ready', { userContextId })[0];
+  const response = sendSyncMessage('juggler:content-ready')[0];
+  // If we didn't get a response, then we don't want to do anything
+  // as a part of this frame script.
+  if (!response)
+    return;
   const {
     sessionIds = [],
     scriptsToEvaluateOnNewDocument = [],
diff --git a/browser_patches/firefox/juggler/protocol/BrowserHandler.js b/browser_patches/firefox/juggler/protocol/BrowserHandler.js
index 3b8f96514d..07ba2567ab 100644
--- a/browser_patches/firefox/juggler/protocol/BrowserHandler.js
+++ b/browser_patches/firefox/juggler/protocol/BrowserHandler.js
@@ -29,7 +29,7 @@ class BrowserHandler {
     this._enabled = true;
     this._attachToDefaultContext = attachToDefaultContext;
 
-    for (const target of this._targetRegistry.targets()) {
+    for (const target of this._targetRegistry.reportedTargets()) {
       if (!this._shouldAttachToTarget(target))
         continue;
       const session = this._dispatcher.createSession();