--- a/mobile/android/base/locales/en-US/sync_strings.dtd
+++ b/mobile/android/base/locales/en-US/sync_strings.dtd
@@ -36,16 +36,18 @@
 <!ENTITY sync.input.server.label 'Server URL'>
   
 <!-- Setup Fail -->
 <!ENTITY sync.title.fail.label 'Cannot Set Up &syncBrand.shortName.label;'>
 <!ENTITY sync.subtitle.fail.label '&syncBrand.fullName.label; could not connect to the server. Would you like to try again?'>
 <!ENTITY sync.button.tryagain.label 'Try again'>
 <!ENTITY sync.button.manual.label 'Manual Setup'>
 <!ENTITY sync.subtitle.nointernet.label 'No internet connection available.'>
+<!ENTITY sync.subtitle.failaccount.label 'Account creation on your device failed.'>
+<!ENTITY sync.subtitle.failmultiple.label 'Do you have more than one Firefox installed? Currently, &syncBrand.fullName.label; only supports one Firefox installation at a time. Please uninstall other instances to use &syncBrand.shortName.label;.'>
   
 <!-- Setup Success -->
 <!ENTITY sync.title.success.label 'Setup Complete'>
 <!ENTITY sync.subtitle.success.label1 'Your data is now being downloaded in the background. You can go to Settings to manage your account, or start browsing with &brandShortName;.'>
 <!ENTITY sync.settings.label 'Settings'>
 <!ENTITY sync.subtitle.manage.label1 'Your &syncBrand.fullName.label; account is already set up. You can go to Settings to manage your account, or launch &brandShortName;.'>
 
 <!-- Pair Device -->

--- a/mobile/android/base/resources/layout/sync_setup_failure.xml
+++ b/mobile/android/base/resources/layout/sync_setup_failure.xml
@@ -11,23 +11,32 @@
   <ImageView
     style="@style/SyncTopIcon" />
   <TextView
     style="@style/SyncTextTitle"
     android:text="@string/sync_title_fail" />
   </LinearLayout>
 
   <TextView
+    android:id="@+id/failure_subtitle1"
     style="@style/SyncTextItem"
     android:layout_below="@id/failure_top"
-    android:layout_above="@+id/failure_bottom"
     android:padding="20dp"
     android:text="@string/sync_subtitle_fail" />
+
+  <TextView
+    android:id="@+id/failure_subtitle2"
+    style="@style/SyncTextItem"
+    android:layout_below="@id/failure_subtitle1"
+    android:paddingLeft="20dp"
+    android:paddingRight="20dp"
+    android:text="@string/sync_subtitle_failmultiple" />
+
   <LinearLayout
-    android:id="@id/failure_bottom"
+    android:id="@+id/failure_bottom"
     style="@style/SyncBottom"
     android:orientation="horizontal" >
 
     <Button
       style="@style/SyncButton"
       android:onClick="tryAgainClickHandler"
       android:text="@string/sync_button_tryagain" />
 

--- a/mobile/android/base/sync/setup/Constants.java
+++ b/mobile/android/base/sync/setup/Constants.java
@@ -32,18 +32,19 @@ public class Constants {
    * <p>
    * Corresponding value should be a String JSON-encoding an object, the keys of
    * which are the stage names to skip. For example:
    * <code>"{ \"stageToSkip\": 0 }"</code>.
    */
   public static final String EXTRAS_KEY_STAGES_TO_SKIP = "skip";
 
   // Constants for Activities.
-  public static final String INTENT_EXTRA_IS_SETUP = "isSetup";
-  public static final String INTENT_EXTRA_IS_PAIR  = "isPair";
+  public static final String INTENT_EXTRA_IS_SETUP        = "isSetup";
+  public static final String INTENT_EXTRA_IS_PAIR         = "isPair";
+  public static final String INTENT_EXTRA_IS_ACCOUNTERROR = "isAccountError";
 
   public static final int FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION =
     Intent.FLAG_ACTIVITY_REORDER_TO_FRONT |
     Intent.FLAG_ACTIVITY_NO_ANIMATION;
 
   // Constants for Account Authentication.
   public static final String AUTH_NODE_DEFAULT    = "https://auth.services.mozilla.com/";
   public static final String AUTH_NODE_PATHNAME   = "user/";

--- a/mobile/android/base/sync/setup/activities/AccountActivity.java
+++ b/mobile/android/base/sync/setup/activities/AccountActivity.java
@@ -248,20 +248,17 @@ public class AccountActivity extends Acc
       public void run() {
         Account account = SyncAccounts.createSyncAccount(syncAccount);
         boolean isSuccess = (account != null);
         if (!isSuccess) {
           setResult(RESULT_CANCELED);
           runOnUiThread(new Runnable() {
             @Override
             public void run() {
-              // Use default error.
-              // TODO: Bug 766499: Show specific error message when Android fails on Account creation.
-              Logger.debug(LOG_TAG, "displayFailure()");
-              displayFailure(AuthenticationResult.FAILURE_OTHER);
+              displayFailure(AuthenticationResult.FAILURE_ACCOUNT);
             }
           });
           return;
         }
 
         // Account created successfully.
         clearErrors();
 
@@ -289,32 +286,39 @@ public class AccountActivity extends Acc
       progressDialog.dismiss();
     }
   }
 
   private void displayFailure(final AuthenticationResult result) {
     runOnUiThread(new Runnable() {
       @Override
       public void run() {
+        Intent intent;
         switch (result) {
         case FAILURE_USERNAME:
           // No such username. Don't leak whether the username exists.
         case FAILURE_PASSWORD:
           findViewById(R.id.cred_error).setVisibility(View.VISIBLE);
           usernameInput.requestFocus();
           break;
         case FAILURE_SERVER:
           findViewById(R.id.server_error).setVisibility(View.VISIBLE);
           serverInput.requestFocus();
           break;
+        case FAILURE_ACCOUNT:
+          intent = new Intent(mContext, SetupFailureActivity.class);
+          intent.setFlags(Constants.FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION);
+          intent.putExtra(Constants.INTENT_EXTRA_IS_ACCOUNTERROR, true);
+          startActivity(intent);
+          break;
         case FAILURE_OTHER:
         default:
           // Display default error screen.
           Logger.debug(LOG_TAG, "displaying default failure.");
-          Intent intent = new Intent(mContext, SetupFailureActivity.class);
+          intent = new Intent(mContext, SetupFailureActivity.class);
           intent.setFlags(Constants.FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION);
           startActivity(intent);
         }
       }
     });
     return;
   }
 

--- a/mobile/android/base/sync/setup/activities/SetupFailureActivity.java
+++ b/mobile/android/base/sync/setup/activities/SetupFailureActivity.java
@@ -1,35 +1,53 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package org.mozilla.gecko.sync.setup.activities;
 
 import org.mozilla.gecko.R;
+import org.mozilla.gecko.sync.setup.Constants;
 
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
+import android.widget.TextView;
 
 public class SetupFailureActivity extends Activity {
   private Context mContext;
 
   @Override
   public void onCreate(Bundle savedInstanceState) {
     setTheme(R.style.SyncTheme);
     super.onCreate(savedInstanceState);
     setContentView(R.layout.sync_setup_failure);
     mContext = this.getApplicationContext();
+
+    // Modify general error message if necessary.
+    Bundle extras = this.getIntent().getExtras();
+    if (extras != null) {
+      boolean isAccountError = extras.getBoolean(Constants.INTENT_EXTRA_IS_ACCOUNTERROR);
+      if (isAccountError) {
+        TextView subtitle1 = (TextView) findViewById(R.id.failure_subtitle1);
+        // Display error for multiple accounts.
+        // TODO: Remove when Bug 761206 is resolved (support for multiple versions).
+        TextView subtitle2 = (TextView) findViewById(R.id.failure_subtitle2);
+        subtitle1.setText(getString(R.string.sync_subtitle_failaccount));
+        subtitle2.setVisibility(View.VISIBLE);
+        subtitle2.setText(getString(R.string.sync_subtitle_failmultiple));
+      }
+    }
   }
 
   public void manualClickHandler(View target) {
     Intent intent = new Intent(mContext, AccountActivity.class);
+    intent.setFlags(Constants.FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION);
     startActivity(intent);
     overridePendingTransition(0, 0);
     finish();
   }
 
   public void tryAgainClickHandler(View target) {
     finish();
   }

--- a/mobile/android/base/sync/setup/activities/SetupSyncActivity.java
+++ b/mobile/android/base/sync/setup/activities/SetupSyncActivity.java
@@ -74,16 +74,23 @@ public class SetupSyncActivity extends A
     setTheme(R.style.SyncTheme);
     Logger.info(LOG_TAG, "Called SetupSyncActivity.onCreate.");
     super.onCreate(savedInstanceState);
 
     // Set Activity variables.
     mContext = getApplicationContext();
     Logger.debug(LOG_TAG, "AccountManager.get(" + mContext + ")");
     mAccountManager = AccountManager.get(mContext);
+
+    // Set "screen on" flag for this activity. Screen will not automatically dim as long as this
+    // activity is at the top of the stack.
+    // Attempting to set this flag more than once causes hanging, so we set it here, not in onResume().
+    Window w = getWindow();
+    w.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+    Logger.debug(LOG_TAG, "Successfully set screen-on flag.");
   }
 
   @Override
   public void onResume() {
     Logger.info(LOG_TAG, "Called SetupSyncActivity.onResume.");
     super.onResume();
 
     if (!hasInternet()) {
@@ -100,21 +107,16 @@ public class SetupSyncActivity extends A
         finishResume(accts);
       }
     });
   }
 
   public void finishResume(Account[] accts) {
     Logger.debug(LOG_TAG, "Finishing Resume after fetching accounts.");
 
-    // Set "screen on" flag.
-    Logger.debug(LOG_TAG, "Setting screen-on flag.");
-    Window w = getWindow();
-    w.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
-
     if (accts.length == 0) { // Start J-PAKE for pairing if no accounts present.
       Logger.debug(LOG_TAG, "No accounts; starting J-PAKE receiver.");
       displayReceiveNoPin();
       if (jClient != null) {
         // Mark previous J-PAKE as finished. Don't bother propagating back up to this Activity.
         jClient.finished = true;
       }
       jClient = new JPakeClient(this);
@@ -426,48 +428,53 @@ public class SetupSyncActivity extends A
           resultBundle.putString(AccountManager.KEY_ACCOUNT_TYPE, Constants.ACCOUNTTYPE_SYNC);
           resultBundle.putString(AccountManager.KEY_AUTHTOKEN, Constants.ACCOUNTTYPE_SYNC);
           setAccountAuthenticatorResult(resultBundle);
         }
         displayResultAndFinish(isSuccess);
       }
     });
   }
+
   /*
    * Helper functions
    */
-
   private void activateButton(Button button, boolean toActivate) {
     button.setEnabled(toActivate);
     button.setClickable(toActivate);
   }
 
   private void enablePinEntry(boolean toEnable) {
     row1.setEnabled(toEnable);
     row2.setEnabled(toEnable);
     row3.setEnabled(toEnable);
   }
 
   /**
    * Displays Sync account setup result to user.
    *
    * @param isSetup
-   *          true is account was set up successfully, false otherwise.
+   *          true if account was set up successfully, false otherwise.
    */
   private void displayResult(boolean isSuccess) {
     Intent intent = null;
     if (isSuccess) {
       intent = new Intent(mContext, SetupSuccessActivity.class);
-    }  else {
+      intent.setFlags(Constants.FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION);
+      intent.putExtra(Constants.INTENT_EXTRA_IS_SETUP, !pairWithPin);
+      startActivity(intent);
+      finish();
+    } else {
       intent = new Intent(mContext, SetupFailureActivity.class);
+      intent.putExtra(Constants.INTENT_EXTRA_IS_ACCOUNTERROR, true);
+      intent.setFlags(Constants.FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION);
+      intent.putExtra(Constants.INTENT_EXTRA_IS_SETUP, !pairWithPin);
+      startActivity(intent);
+      // Do not finish, so user can retry setup by hitting "back."
     }
-    intent.setFlags(Constants.FLAG_ACTIVITY_REORDER_TO_FRONT_NO_ANIMATION);
-    intent.putExtra(Constants.INTENT_EXTRA_IS_SETUP, !pairWithPin);
-    startActivity(intent);
-    finish();
   }
 
   /**
    * Validate PIN entry fields to check if the three PIN entry fields are all
    * filled in.
    *
    * @return true, if all PIN fields have 4 characters, false otherwise
    */

--- a/mobile/android/base/sync/setup/auth/AuthenticationResult.java
+++ b/mobile/android/base/sync/setup/auth/AuthenticationResult.java
@@ -1,9 +1,9 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package org.mozilla.gecko.sync.setup.auth;
 
 public enum AuthenticationResult {
-  SUCCESS, FAILURE_USERNAME, FAILURE_PASSWORD, FAILURE_SERVER, FAILURE_OTHER
+  SUCCESS, FAILURE_USERNAME, FAILURE_PASSWORD, FAILURE_SERVER, FAILURE_ACCOUNT, FAILURE_OTHER
 }

--- a/mobile/android/sync/strings.xml.in
+++ b/mobile/android/sync/strings.xml.in
@@ -30,16 +30,18 @@
   <string name="sync_input_server">&sync.input.server.label;</string>
   
   <!-- Setup Fail -->
   <string name="sync_title_fail">&sync.title.fail.label;</string>
   <string name="sync_subtitle_fail">&sync.subtitle.fail.label;</string>
   <string name="sync_button_tryagain">&sync.button.tryagain.label;</string>
   <string name="sync_button_manual">&sync.button.manual.label;</string>
   <string name="sync_subtitle_nointernet">&sync.subtitle.nointernet.label;</string>
+  <string name="sync_subtitle_failaccount">&sync.subtitle.failaccount.label;</string>
+  <string name="sync_subtitle_failmultiple">&sync.subtitle.failmultiple.label;</string>
   
   <!-- Setup Success -->
   <string name="sync_title_success">&sync.title.success.label;</string>
   <string name="sync_subtitle_success">&sync.subtitle.success.label1;</string>
   <string name="sync_settings">&sync.settings.label;</string>
   <string name="sync_subtitle_manage">&sync.subtitle.manage.label1;</string>
   
   <!-- Pair Device -->