--- a/mobile/android/base/favicons/Favicons.java
+++ b/mobile/android/base/favicons/Favicons.java
@@ -346,16 +346,17 @@ public class Favicons {
         try {
             // Fall back to trying "someScheme:someDomain.someExtension/favicon.ico".
             URI u = new URI(pageURL);
             return new URI(u.getScheme(),
                            u.getAuthority(),
                            "/favicon.ico", null,
                            null).toString();
         } catch (URISyntaxException e) {
+            Log.e(LOGTAG, "URISyntaxException getting default favicon URL", e);
             return null;
         }
     }
 
     public static void removeLoadTask(long taskId) {
         sLoadTasks.remove(taskId);
     }
 

--- a/mobile/android/base/favicons/LoadFaviconTask.java
+++ b/mobile/android/base/favicons/LoadFaviconTask.java
@@ -229,16 +229,20 @@ public class LoadFaviconTask extends UiA
             }
 
             // If we found a faviconURL - use it.
             if (storedFaviconUrl != null) {
                 mFaviconUrl = storedFaviconUrl;
             } else {
                 // If we don't have a stored one, fall back to the default.
                 mFaviconUrl = Favicons.guessDefaultFaviconURL(mPageUrl);
+
+                if (TextUtils.isEmpty(mFaviconUrl)) {
+                    return null;
+                }
                 isUsingDefaultURL = true;
             }
         }
 
         // Check if favicon has failed - if so, give up. We need this check because, sometimes, we
         // didn't know the real Favicon URL until we asked the database.
         if (Favicons.isFailedFavicon(mFaviconUrl)) {
             return null;

--- a/mobile/android/base/favicons/cache/FaviconCache.java
+++ b/mobile/android/base/favicons/cache/FaviconCache.java
@@ -200,16 +200,20 @@ public class FaviconCache {
     /**
      * Determine if the provided favicon URL is marked as a failure (Has failed to load before -
      * such icons get blacklisted for a time to prevent us endlessly retrying.)
      *
      * @param faviconURL Favicon URL to check if failed in memcache.
      * @return true if this favicon is blacklisted, false otherwise.
      */
     public boolean isFailedFavicon(String faviconURL) {
+        if (faviconURL == null) {
+            return true;
+        }
+
         startRead();
 
         boolean isExpired = false;
         boolean isAborting = false;
 
         try {
             // If we don't have it in the cache, it certainly isn't a known failure.
             if (!mBackingMap.containsKey(faviconURL)) {
@@ -236,17 +240,17 @@ public class FaviconCache {
             }
         } catch (Exception unhandled) {
             // Handle any exception thrown and return the locks to a sensible state.
             finishRead();
 
             // Flag to prevent finally from doubly-unlocking.
             isAborting = true;
             Log.e(LOGTAG, "FaviconCache exception!", unhandled);
-            return false;
+            return true;
         }  finally {
             if (!isAborting) {
                 if (isExpired) {
                     // No longer expired.
                     upgradeReadToWrite();
                 } else {
                     finishRead();
                 }