diff --git a/src/com/android/launcher3/LauncherModel.java b/src/com/android/launcher3/LauncherModel.java
index a386ebd..636af7d 100644
--- a/src/com/android/launcher3/LauncherModel.java
+++ b/src/com/android/launcher3/LauncherModel.java
@@ -1607,11 +1607,12 @@
         }
 
         // check & update map of what's occupied; used to discard overlapping/invalid items
-        private boolean checkItemPlacement(LongArrayMap<ItemInfo[][]> occupied, ItemInfo item) {
+        private boolean checkItemPlacement(LongArrayMap<ItemInfo[][]> occupied, ItemInfo item,
+                   ArrayList<Long> workspaceScreens) {
             LauncherAppState app = LauncherAppState.getInstance();
             InvariantDeviceProfile profile = app.getInvariantDeviceProfile();
-            final int countX = (int) profile.numColumns;
-            final int countY = (int) profile.numRows;
+            final int countX = profile.numColumns;
+            final int countY = profile.numRows;
 
             long containerIndex = item.screenId;
             if (item.container == LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
@@ -1653,7 +1654,12 @@
                     occupied.put((long) LauncherSettings.Favorites.CONTAINER_HOTSEAT, items);
                     return true;
                 }
-            } else if (item.container != LauncherSettings.Favorites.CONTAINER_DESKTOP) {
+            } else if (item.container == LauncherSettings.Favorites.CONTAINER_DESKTOP) {
+                if (!workspaceScreens.contains((Long) item.screenId)) {
+                    // The item has an invalid screen id.
+                    return false;
+                }
+            } else {
                 // Skip further checking if it is not the hotseat or workspace container
                 return true;
             }
@@ -1719,8 +1725,8 @@
 
             LauncherAppState app = LauncherAppState.getInstance();
             InvariantDeviceProfile profile = app.getInvariantDeviceProfile();
-            int countX = (int) profile.numColumns;
-            int countY = (int) profile.numRows;
+            int countX = profile.numColumns;
+            int countY = profile.numRows;
 
             if (MigrateFromRestoreTask.ENABLED && MigrateFromRestoreTask.shouldRunTask(mContext)) {
                 long migrationStartTime = System.currentTimeMillis();
@@ -1760,6 +1766,7 @@
                 clearSBgDataStructures();
                 final HashMap<String, Integer> installingPkgs = PackageInstallerCompat
                         .getInstance(mContext).updateAndGetActiveSessionCache();
+                sBgWorkspaceScreens.addAll(loadWorkspaceScreensDb(mContext));
 
                 final ArrayList<Long> itemsToRemove = new ArrayList<Long>();
                 final ArrayList<Long> restoredRows = new ArrayList<Long>();
@@ -1961,6 +1968,7 @@
                                 } catch (URISyntaxException e) {
                                     Launcher.addDumpLog(TAG,
                                             "Invalid uri: " + intentDescription, true);
+                                    itemsToRemove.add(id);
                                     continue;
                                 }
 
@@ -2031,7 +2039,7 @@
                                     }
 
                                     // check & update map of what's occupied
-                                    if (!checkItemPlacement(occupied, info)) {
+                                    if (!checkItemPlacement(occupied, info, sBgWorkspaceScreens)) {
                                         itemsToRemove.add(id);
                                         break;
                                     }
@@ -2082,7 +2090,7 @@
                                 folderInfo.options = c.getInt(optionsIndex);
 
                                 // check & update map of what's occupied
-                                if (!checkItemPlacement(occupied, folderInfo)) {
+                                if (!checkItemPlacement(occupied, folderInfo, sBgWorkspaceScreens)) {
                                     itemsToRemove.add(id);
                                     break;
                                 }
@@ -2202,13 +2210,14 @@
                                     if (container != LauncherSettings.Favorites.CONTAINER_DESKTOP &&
                                         container != LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
                                         Log.e(TAG, "Widget found where container != " +
-                                            "CONTAINER_DESKTOP nor CONTAINER_HOTSEAT - ignoring!");
+                                                "CONTAINER_DESKTOP nor CONTAINER_HOTSEAT - ignoring!");
+                                        itemsToRemove.add(id);
                                         continue;
                                     }
 
                                     appWidgetInfo.container = container;
                                     // check & update map of what's occupied
-                                    if (!checkItemPlacement(occupied, appWidgetInfo)) {
+                                    if (!checkItemPlacement(occupied, appWidgetInfo, sBgWorkspaceScreens)) {
                                         itemsToRemove.add(id);
                                         break;
                                     }
@@ -2297,8 +2306,6 @@
                             null, sWorker);
                 }
 
-                sBgWorkspaceScreens.addAll(loadWorkspaceScreensDb(mContext));
-
                 // Remove any empty screens
                 ArrayList<Long> unusedScreens = new ArrayList<Long>(sBgWorkspaceScreens);
                 for (ItemInfo item: sBgItemsIdMap) {
diff --git a/src/com/android/launcher3/LauncherProvider.java b/src/com/android/launcher3/LauncherProvider.java
index 44a43e1..c6827da 100644
--- a/src/com/android/launcher3/LauncherProvider.java
+++ b/src/com/android/launcher3/LauncherProvider.java
@@ -65,12 +65,11 @@
 import java.util.List;
 
 public class LauncherProvider extends ContentProvider {
-    private static final String TAG = "Launcher.LauncherProvider";
+    private static final String TAG = "LauncherProvider";
     private static final boolean LOGD = false;
 
     private static final int DATABASE_VERSION = 26;
 
-    static final String OLD_AUTHORITY = "com.android.launcher2.settings";
     public static final String AUTHORITY = ProviderConfig.AUTHORITY;
 
     static final String TABLE_FAVORITES = LauncherSettings.Favorites.TABLE_NAME;
@@ -139,7 +138,7 @@
     }
 
     private void reloadLauncherIfExternal() {
-        if (Binder.getCallingPid() != Process.myPid()) {
+        if (Utilities.ATLEAST_MARSHMALLOW && Binder.getCallingPid() != Process.myPid()) {
             LauncherAppState app = LauncherAppState.getInstanceNoCreate();
             if (app != null) {
                 app.reloadWorkspace();
@@ -166,7 +165,20 @@
         uri = ContentUris.withAppendedId(uri, rowId);
         notifyListeners();
 
-        reloadLauncherIfExternal();
+        if (Utilities.ATLEAST_MARSHMALLOW) {
+            reloadLauncherIfExternal();
+        } else {
+            // Deprecated behavior to support legacy devices which rely on provider callbacks.
+            LauncherAppState app = LauncherAppState.getInstanceNoCreate();
+            if (app != null && "true".equals(uri.getQueryParameter("isExternalAdd"))) {
+                app.reloadWorkspace();
+            }
+
+            String notify = uri.getQueryParameter("notify");
+            if (notify == null || "true".equals(notify)) {
+                getContext().getContentResolver().notifyChange(uri, null);
+            }
+        }
         return uri;
     }