--- a/mobile/android/base/java/org/mozilla/gecko/GeckoApp.java
+++ b/mobile/android/base/java/org/mozilla/gecko/GeckoApp.java
@@ -2131,16 +2131,18 @@ public abstract class GeckoApp extends G
 
                     editor.putBoolean(GeckoApp.PREFS_CLEANUP_TEMP_FILES, false);
                 }
 
                 editor.apply();
             }
         });
 
+        GeckoAppShell.setScreenOrientationDelegate(null);
+
         super.onPause();
     }
 
     @Override
     public void onRestart() {
         if (mIsAbortingAppLaunch) {
             super.onRestart();
             return;

--- a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoAppShell.java
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoAppShell.java
@@ -79,16 +79,17 @@ import android.os.Bundle;
 import android.os.Environment;
 import android.os.Looper;
 import android.os.ParcelFileDescriptor;
 import android.os.PowerManager;
 import android.os.SystemClock;
 import android.os.Vibrator;
 import android.provider.Settings;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.support.v4.util.SimpleArrayMap;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 import android.util.DisplayMetrics;
 import android.util.Log;
 import android.view.ContextThemeWrapper;
 import android.view.Display;
 import android.view.HapticFeedbackConstants;
@@ -623,17 +624,17 @@ public class GeckoAppShell
     public static void setNotificationListener(final NotificationListener listener) {
         sNotificationListener = (listener != null) ? listener : DEFAULT_LISTENERS;
     }
 
     public static ScreenOrientationDelegate getScreenOrientationDelegate() {
         return sScreenOrientationDelegate;
     }
 
-    public static void setScreenOrientationDelegate(ScreenOrientationDelegate screenOrientationDelegate) {
+    public static void setScreenOrientationDelegate(@Nullable ScreenOrientationDelegate screenOrientationDelegate) {
         sScreenOrientationDelegate = (screenOrientationDelegate != null) ? screenOrientationDelegate : DEFAULT_LISTENERS;
     }
 
     public static WakeLockDelegate getWakeLockDelegate() {
         return sWakeLockDelegate;
     }
 
     public void setWakeLockDelegate(final WakeLockDelegate delegate) {