--- a/browser/base/content/tab-content.js
+++ b/browser/base/content/tab-content.js
@@ -255,17 +255,17 @@ var AboutPrivateBrowsingListener = {
   },
 };
 AboutPrivateBrowsingListener.init(this);
 
 var AboutReaderListener = {
 
   _articlePromise: null,
 
-  _isLeavingReaderMode: false,
+  _isLeavingReaderableReaderMode: false,
 
   init() {
     addEventListener("AboutReaderContentLoaded", this, false, true);
     addEventListener("DOMContentLoaded", this, false);
     addEventListener("pageshow", this, false);
     addEventListener("pagehide", this, false);
     addMessageListener("Reader:ToggleReaderMode", this);
     addMessageListener("Reader:PushState", this);
@@ -273,17 +273,17 @@ var AboutReaderListener = {
 
   receiveMessage(message) {
     switch (message.name) {
       case "Reader:ToggleReaderMode":
         if (!this.isAboutReader) {
           this._articlePromise = ReaderMode.parseDocument(content.document).catch(Cu.reportError);
           ReaderMode.enterReaderMode(docShell, content);
         } else {
-          this._isLeavingReaderMode = true;
+          this._isLeavingReaderableReaderMode = this.isReaderableAboutReader;
           ReaderMode.leaveReaderMode(docShell, content);
         }
         break;
 
       case "Reader:PushState":
         this.updateReaderButton(!!(message.data && message.data.isArticle));
         break;
     }
@@ -291,16 +291,21 @@ var AboutReaderListener = {
 
   get isAboutReader() {
     if (!content) {
       return false;
     }
     return content.document.documentURI.startsWith("about:reader");
   },
 
+  get isReaderableAboutReader() {
+    return this.isAboutReader &&
+      !content.document.documentElement.dataset.isError;
+  },
+
   handleEvent(aEvent) {
     if (aEvent.originalTarget.defaultView != content) {
       return;
     }
 
     switch (aEvent.type) {
       case "AboutReaderContentLoaded":
         if (!this.isAboutReader) {
@@ -312,22 +317,22 @@ var AboutReaderListener = {
           sendAsyncMessage("Reader:UpdateReaderButton");
           new AboutReader(global, content, this._articlePromise);
           this._articlePromise = null;
         }
         break;
 
       case "pagehide":
         this.cancelPotentialPendingReadabilityCheck();
-        // this._isLeavingReaderMode is used here to keep the Reader Mode icon
+        // this._isLeavingReaderableReaderMode is used here to keep the Reader Mode icon
         // visible in the location bar when transitioning from reader-mode page
-        // back to the source page.
-        sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: this._isLeavingReaderMode });
-        if (this._isLeavingReaderMode) {
-          this._isLeavingReaderMode = false;
+        // back to the readable source page.
+        sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: this._isLeavingReaderableReaderMode });
+        if (this._isLeavingReaderableReaderMode) {
+          this._isLeavingReaderableReaderMode = false;
         }
         break;
 
       case "pageshow":
         // If a page is loaded from the bfcache, we won't get a "DOMContentLoaded"
         // event, so we need to rely on "pageshow" in this case.
         if (aEvent.persisted) {
           this.updateReaderButton();

--- a/mobile/android/chrome/content/content.js
+++ b/mobile/android/chrome/content/content.js
@@ -17,17 +17,17 @@ var dump = Cu.import("resource://gre/mod
 
 var global = this;
 
 // This is copied from desktop's tab-content.js. See bug 1153485 about sharing this code somehow.
 var AboutReaderListener = {
 
   _articlePromise: null,
 
-  _isLeavingReaderMode: false,
+  _isLeavingReaderableReaderMode: false,
 
   init: function() {
     addEventListener("AboutReaderContentLoaded", this, false, true);
     addEventListener("DOMContentLoaded", this, false);
     addEventListener("pageshow", this, false);
     addEventListener("pagehide", this, false);
     addMessageListener("Reader:ToggleReaderMode", this);
     addMessageListener("Reader:PushState", this);
@@ -36,31 +36,36 @@ var AboutReaderListener = {
   receiveMessage: function(message) {
     switch (message.name) {
       case "Reader:ToggleReaderMode":
         let url = content.document.location.href;
         if (!this.isAboutReader) {
           this._articlePromise = ReaderMode.parseDocument(content.document).catch(Cu.reportError);
           ReaderMode.enterReaderMode(docShell, content);
         } else {
-          this._isLeavingReaderMode = true;
+          this._isLeavingReaderableReaderMode = this.isReaderableAboutReader;
           ReaderMode.leaveReaderMode(docShell, content);
         }
         break;
 
       case "Reader:PushState":
         this.updateReaderButton(!!(message.data && message.data.isArticle));
         break;
     }
   },
 
   get isAboutReader() {
     return content.document.documentURI.startsWith("about:reader");
   },
 
+  get isReaderableAboutReader() {
+    return this.isAboutReader &&
+      !content.document.documentElement.dataset.isError;
+  },
+
   get isErrorPage() {
     return content.document.documentURI.startsWith("about:neterror") ||
         content.document.documentURI.startsWith("about:certerror") ||
         content.document.documentURI.startsWith("about:blocked");
   },
 
   handleEvent: function(aEvent) {
     if (aEvent.originalTarget.defaultView != content) {
@@ -79,22 +84,22 @@ var AboutReaderListener = {
         // valid message will follow. See bug 925983.
         if (content.document.body) {
           new AboutReader(global, content, this._articlePromise);
           this._articlePromise = null;
         }
         break;
 
       case "pagehide":
-        // this._isLeavingReaderMode is used here to keep the Reader Mode icon
+        // this._isLeavingReaderableReaderMode is used here to keep the Reader Mode icon
         // visible in the location bar when transitioning from reader-mode page
         // back to the source page.
-        sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: this._isLeavingReaderMode });
-        if (this._isLeavingReaderMode) {
-          this._isLeavingReaderMode = false;
+        sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: this._isLeavingReaderableReaderMode });
+        if (this._isLeavingReaderableReaderMode) {
+          this._isLeavingReaderableReaderMode = false;
         }
         break;
 
       case "pageshow":
         // If a page is loaded from the bfcache, we won't get a "DOMContentLoaded"
         // event, so we need to rely on "pageshow" in this case.
         if (aEvent.persisted) {
           this.updateReaderButton();

--- a/toolkit/components/reader/AboutReader.jsm
+++ b/toolkit/components/reader/AboutReader.jsm
@@ -757,17 +757,22 @@ AboutReader.prototype = {
     this._contentElement.style.display = "none";
 
     let errorMessage = gStrings.GetStringFromName("aboutReader.loadError");
     this._messageElement.textContent = errorMessage;
     this._messageElement.style.display = "block";
 
     this._doc.title = errorMessage;
 
+    this._doc.documentElement.dataset.isError = true;
+
     this._error = true;
+
+    this._doc.dispatchEvent(
+      new this._win.CustomEvent("AboutReaderContentError", { bubbles: true, cancelable: false }));
   },
 
   // This function is the JS version of Java's StringUtils.stripCommonSubdomains.
   _stripHost(host) {
     if (!host)
       return host;
 
     let start = 0;

--- a/toolkit/components/reader/test/browser.ini
+++ b/toolkit/components/reader/test/browser.ini
@@ -1,12 +1,13 @@
 [DEFAULT]
 support-files = head.js
 [browser_readerMode.js]
 support-files =
+  readerModeNonArticle.html
   readerModeArticle.html
   readerModeArticleHiddenNodes.html
 [browser_readerMode_hidden_nodes.js]
 support-files =
   readerModeArticleHiddenNodes.html
 [browser_readerMode_with_anchor.js]
 support-files =
   readerModeArticle.html

--- a/toolkit/components/reader/test/browser_readerMode.js
+++ b/toolkit/components/reader/test/browser_readerMode.js
@@ -48,18 +48,19 @@ add_task(function* test_reader_button() 
   yield tourPopupShownPromise;
   is_element_visible(readerButton, "Reader mode button is present on a reader-able page");
   ok(UITour.isInfoOnTarget(window, "readerMode-urlBar"),
      "Info panel should be anchored at the reader mode button");
   ok(Services.prefs.getBoolPref("browser.reader.detectedFirstArticle"),
      "Should have detected the first article");
 
   // Switch page into reader mode.
+  let promiseTabLoad = promiseTabLoadEvent(tab);
   readerButton.click();
-  yield promiseTabLoadEvent(tab);
+  yield promiseTabLoad;
   ok(!UITour.isInfoOnTarget(window, "readerMode-urlBar"), "Info panel should have closed");
 
   let readerUrl = gBrowser.selectedBrowser.currentURI.spec;
   ok(readerUrl.startsWith("about:reader"), "about:reader loaded after clicking reader mode button");
   is_element_visible(readerButton, "Reader mode button is present on about:reader");
 
   is(gURLBar.value, readerUrl, "gURLBar value is about:reader URL");
   is(gURLBar.textValue, url.substring("http://".length), "gURLBar is displaying original article URL");
@@ -79,26 +80,45 @@ add_task(function* test_reader_button() 
   let promisePageShow = BrowserTestUtils.waitForContentEvent(tab.linkedBrowser, "pageshow");
   readerButton.click();
   yield promisePageShow;
   is(gBrowser.selectedBrowser.currentURI.spec, url,
     "Back to the original page after clicking active reader mode button");
   ok(gBrowser.selectedBrowser.canGoForward,
     "Moved one step back in the session history.");
 
+  let nonReadableUrl = TEST_PATH + "readerModeNonArticle.html";
+
   // Load a new tab that is NOT reader-able.
   let newTab = gBrowser.selectedTab = gBrowser.addTab();
-  yield promiseTabLoadEvent(newTab, "about:robots");
+  yield promiseTabLoadEvent(newTab, nonReadableUrl);
   yield promiseWaitForCondition(() => readerButton.hidden);
   is_element_hidden(readerButton, "Reader mode button is not present on a non-reader-able page");
 
   // Switch back to the original tab to make sure reader mode button is still visible.
   gBrowser.removeCurrentTab();
   yield promiseWaitForCondition(() => !readerButton.hidden);
   is_element_visible(readerButton, "Reader mode button is present on a reader-able page");
+
+  // Load a new tab in reader mode that is NOT reader-able in the reader mode.
+  newTab = gBrowser.selectedTab = gBrowser.addTab();
+  let promiseAboutReaderError = BrowserTestUtils.waitForContentEvent(newTab.linkedBrowser, "AboutReaderContentError");
+  yield promiseTabLoadEvent(newTab, "about:reader?url=" + nonReadableUrl);
+  yield promiseAboutReaderError;
+  yield promiseWaitForCondition(() => !readerButton.hidden);
+  is_element_visible(readerButton, "Reader mode button is present on about:reader even in error state");
+
+  // Switch page back out of reader mode.
+  promisePageShow = BrowserTestUtils.waitForContentEvent(newTab.linkedBrowser, "pageshow");
+  readerButton.click();
+  yield promisePageShow;
+  is(gBrowser.selectedBrowser.currentURI.spec, nonReadableUrl,
+    "Back to the original non-reader-able page after clicking active reader mode button");
+  yield promiseWaitForCondition(() => readerButton.hidden);
+  is_element_hidden(readerButton, "Reader mode button is not present on a non-reader-able page");
 });
 
 add_task(function* test_getOriginalUrl() {
   let { ReaderMode } = Cu.import("resource://gre/modules/ReaderMode.jsm", {});
   let url = "http://foo.com/article.html";
 
   is(ReaderMode.getOriginalUrl("about:reader?url=" + encodeURIComponent(url)), url, "Found original URL from encoded URL");
   is(ReaderMode.getOriginalUrl("about:reader?foobar"), null, "Did not find original URL from malformed reader URL");

new file mode 100644
--- /dev/null
+++ b/toolkit/components/reader/test/readerModeNonArticle.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title>Non article title</title>
+<meta name="description" content="This is the non-article description." />
+</head>
+<body>
+<header>Site header</header>
+<div>
+<h1>Non article title</h1>
+<p>Woot!</p>
+</div>
+</body>
+</html>