--- a/mobile/android/base/java/org/mozilla/gecko/BrowserApp.java
+++ b/mobile/android/base/java/org/mozilla/gecko/BrowserApp.java
@@ -651,19 +651,30 @@ public class BrowserApp extends GeckoApp
 
         // Initialize Tab History Controller.
         tabHistoryController = new TabHistoryController(new OnShowTabHistory() {
             @Override
             public void onShowHistory(final List<TabHistoryPage> historyPageList, final int toIndex) {
                 runOnUiThread(new Runnable() {
                     @Override
                     public void run() {
+                        if (BrowserApp.this.isFinishing()) {
+                            // TabHistoryController is rather slow - and involves calling into Gecko
+                            // to retrieve tab history. That means there can be a significant
+                            // delay between the back-button long-press, and onShowHistory()
+                            // being called. Hence we need to guard against the Activity being
+                            // shut down (in which case trying to perform UI changes, such as showing
+                            // fragments below, will crash).
+                            return;
+                        }
+
                         final TabHistoryFragment fragment = TabHistoryFragment.newInstance(historyPageList, toIndex);
                         final FragmentManager fragmentManager = getSupportFragmentManager();
                         GeckoAppShell.vibrateOnHapticFeedbackEnabled(getResources().getIntArray(R.array.long_press_vibrate_msec));
+                        if (BrowserApp.this.isForegrounded())
                         fragment.show(R.id.tab_history_panel, fragmentManager.beginTransaction(), TAB_HISTORY_FRAGMENT_TAG);
                     }
                 });
             }
         });
         mBrowserToolbar.setTabHistoryController(tabHistoryController);
 
         final String action = intent.getAction();
@@ -1064,16 +1075,17 @@ public class BrowserApp extends GeckoApp
         if (urls != null) {
             openUrls(urls);
         }
     }
 
     @Override
     public void onResume() {
         super.onResume();
+
         if (mIsAbortingAppLaunch) {
             return;
         }
 
         if (!mHasResumed) {
             getAppEventDispatcher().unregisterUiThreadListener(this, "Prompt:ShowTop");
             mHasResumed = true;
         }

--- a/mobile/android/base/java/org/mozilla/gecko/tabs/TabHistoryFragment.java
+++ b/mobile/android/base/java/org/mozilla/gecko/tabs/TabHistoryFragment.java
@@ -119,17 +119,20 @@ public class TabHistoryFragment extends 
     }
 
     // Function to add this fragment to activity state with containerViewId as parent.
     // This similar in functionality to DialogFragment.show() except that containerId is provided here.
     public void show(final int containerViewId, final FragmentTransaction transaction, final String tag) {
         dismissed = false;
         transaction.add(containerViewId, this, tag);
         transaction.addToBackStack(tag);
-        backStackId = transaction.commit();
+        // Populating the tab history requires a gecko call (which can be slow) - therefore the app
+        // state by the time we try to show this fragment is unknown, and we could be in the
+        // middle of shutting down:
+        backStackId = transaction.commitAllowingStateLoss();
     }
 
     // Pop the fragment from backstack if it exists.
     public void dismiss() {
         if (dismissed) {
             return;
         }