--- a/browser/components/syncedtabs/TabListView.js
+++ b/browser/components/syncedtabs/TabListView.js
@@ -237,18 +237,20 @@ TabListView.prototype = {
     }
     if (item.focused) {
       itemNode.focus();
     }
     itemNode.dataset.url = item.url;
 
     itemNode.querySelector(".item-title").textContent = item.title;
 
-    let icon = itemNode.querySelector(".item-icon-container");
-    icon.style.backgroundImage = "url(" + item.icon + ")";
+    if (item.icon) {
+      let icon = itemNode.querySelector(".item-icon-container");
+      icon.style.backgroundImage = "url(" + item.icon + ")";
+    }
   },
 
   onClick(event) {
     let itemNode = this._findParentItemNode(event.target);
     if (!itemNode) {
       return;
     }
 

--- a/browser/themes/shared/syncedtabs/sidebar.inc.css
+++ b/browser/themes/shared/syncedtabs/sidebar.inc.css
@@ -79,20 +79,31 @@ body {
 .item.selected:focus > .item-title-container {
   background-color: Highlight;
   color: HighlightText;
 }
 
 .client .item.tab > .item-title-container {
   padding-inline-start: 35px;
 }
+
 .item.tab > .item-title-container {
   padding-inline-start: 20px;
 }
 
+.item.tab > .item-title-container > .item-icon-container {
+  background-image: url("chrome://mozapps/skin/places/defaultFavicon.png");
+}
+
+@media (min-resolution: 1.1dppx) {
+.item.tab > .item-title-container > .item-icon-container {
+    background-image: url("chrome://mozapps/skin/places/defaultFavicon@2x.png");
+  }
+}
+
 .item-icon-container {
   min-width: 16px;
   max-width: 16px;
   min-height: 16px;
   max-height: 16px;
   margin-right: 5px;
   margin-left: 5px;
   background-size: 16px 16px;

--- a/services/sync/modules/SyncedTabs.jsm
+++ b/services/sync/modules/SyncedTabs.jsm
@@ -68,17 +68,17 @@ let SyncedTabsInternal = {
       icon = tab.icon;
     }
     if (!icon) {
       try {
         icon = (yield PlacesUtils.promiseFaviconLinkUrl(url)).spec;
       } catch (ex) { /* no favicon avaiable */ }
     }
     if (!icon) {
-      icon = PlacesUtils.favicons.defaultFavicon.spec;
+      icon = "";
     }
     return {
       type:  "tab",
       title: tab.title || url,
       url,
       icon,
       client: client.id,
       lastUsed: tab.lastUsed,

--- a/services/sync/tests/unit/test_syncedtabs.js
+++ b/services/sync/tests/unit/test_syncedtabs.js
@@ -152,18 +152,18 @@ add_task(function* test_clientWithTabsIc
     },
   });
 
   let clients = yield SyncedTabs.getTabClients();
   equal(clients.length, 1);
   clients.sort((a, b) => { return a.name.localeCompare(b.name);});
   equal(clients[0].tabs.length, 1);
   equal(clients[0].tabs[0].url, "http://foo.com/");
-  // expect the default favicon due to the pref being false.
-  equal(clients[0].tabs[0].icon, faviconService.defaultFavicon.spec);
+  // expect the default favicon (empty string) due to the pref being false.
+  equal(clients[0].tabs[0].icon, "");
   Services.prefs.clearUserPref("services.sync.syncedTabs.showRemoteIcons");
 });
 
 add_task(function* test_filter() {
   // Nothing matches.
   yield configureClients({
     guid_desktop: {
       clientName: "My Desktop",

--- a/toolkit/mozapps/extensions/content/extensions.js
+++ b/toolkit/mozapps/extensions/content/extensions.js
@@ -2250,17 +2250,17 @@ var gDiscoverView = {
     aRequest.cancel(Components.results.NS_BINDING_ABORTED);
   },
 
   onStateChange: function(aWebProgress, aRequest, aStateFlags, aStatus) {
     let transferStart = Ci.nsIWebProgressListener.STATE_IS_DOCUMENT |
                         Ci.nsIWebProgressListener.STATE_IS_REQUEST |
                         Ci.nsIWebProgressListener.STATE_TRANSFERRING;
     // Once transferring begins show the content
-    if (aStateFlags & transferStart)
+    if ((aStateFlags & transferStart) === transferStart)
       this.node.selectedPanel = this._browser;
 
     // Only care about the network events
     if (!(aStateFlags & (Ci.nsIWebProgressListener.STATE_IS_NETWORK)))
       return;
 
     // If this is the start of network activity then show the loading page
     if (aStateFlags & (Ci.nsIWebProgressListener.STATE_START))

--- a/toolkit/mozapps/extensions/test/browser/browser_discovery.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_discovery.js
@@ -630,8 +630,22 @@ add_test(function() {
   open_manager(null, function(aWindow) {
     gManagerWindow = aWindow;
     gCategoryUtilities = new CategoryUtilities(gManagerWindow);
     is(gCategoryUtilities.selectedCategory, "extension", "Should be showing the extension view");
     close_manager(gManagerWindow, run_next_test);
     Services.prefs.clearUserPref(PREF_DISCOVER_ENABLED);
   });
 });
+
+// Test for Bug 1219495 - should show placeholder content when offline
+add_test(function() {
+  // set a URL to cause an error
+  Services.prefs.setCharPref(PREF_DISCOVERURL, "https://nocert.example.com/");
+
+  open_manager("addons://discover/", function(aWindow) {
+    gManagerWindow = aWindow;
+
+    ok(isError(), "Should have shown the placeholder content");
+
+    close_manager(gManagerWindow, run_next_test);
+  });
+});