diff --git a/app/src/main/java/org/fdroid/fdroid/AppDetails.java b/app/src/main/java/org/fdroid/fdroid/AppDetails.java
index 524b35a09..1def0e6ed 100644
--- a/app/src/main/java/org/fdroid/fdroid/AppDetails.java
+++ b/app/src/main/java/org/fdroid/fdroid/AppDetails.java
@@ -1525,8 +1525,10 @@ public class AppDetails extends AppCompatActivity {
 
         public void startProgress(boolean allowCancel) {
             cancelButton.setVisibility(allowCancel ? View.VISIBLE : View.GONE);
-            showIndeterminateProgress(getString(R.string.download_pending));
-            updateViews();
+            if (isAdded()) {
+                showIndeterminateProgress(getString(R.string.download_pending));
+                updateViews();
+            }
         }
 
         private void showIndeterminateProgress(String message) {
diff --git a/app/src/main/java/org/fdroid/fdroid/Preferences.java b/app/src/main/java/org/fdroid/fdroid/Preferences.java
index 7a5b91bed..cfe402d47 100644
--- a/app/src/main/java/org/fdroid/fdroid/Preferences.java
+++ b/app/src/main/java/org/fdroid/fdroid/Preferences.java
@@ -231,7 +231,7 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
         return preferences.getBoolean(PREF_AUTO_DOWNLOAD_INSTALL_UPDATES, false);
     }
 
-    public boolean isUpdateOnlyOnWifi() {
+    public boolean isUpdateOnlyOnUnmeteredNetworks() {
         return preferences.getBoolean(PREF_UPD_WIFI_ONLY, false);
     }
 
diff --git a/app/src/main/java/org/fdroid/fdroid/UpdateService.java b/app/src/main/java/org/fdroid/fdroid/UpdateService.java
index 143f67d19..fbf780caa 100644
--- a/app/src/main/java/org/fdroid/fdroid/UpdateService.java
+++ b/app/src/main/java/org/fdroid/fdroid/UpdateService.java
@@ -31,6 +31,8 @@ import android.database.Cursor;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
 import android.os.Process;
 import android.os.SystemClock;
 import android.preference.PreferenceManager;
@@ -79,6 +81,12 @@ public class UpdateService extends IntentService {
     private static final int NOTIFY_ID_UPDATING = 0;
     private static final int NOTIFY_ID_UPDATES_AVAILABLE = 1;
 
+    private static final int FLAG_NET_UNAVAILABLE = 0;
+    private static final int FLAG_NET_METERED = 1;
+    private static final int FLAG_NET_NO_LIMIT = 2;
+
+    private static Handler toastHandler;
+
     private NotificationManager notificationManager;
     private NotificationCompat.Builder notificationBuilder;
 
@@ -279,26 +287,50 @@ public class UpdateService extends IntentService {
             return false;
         }
 
-        return isNetworkAvailableForUpdate(this);
+        return true;
     }
 
     /**
-     * If we are to update the repos only on wifi, make sure that connection is active
+     * Gets the state of internet availability, whether there is no connection at all,
+     * whether the connection has no usage limit (like most WiFi), or whether this is
+     * a metered connection like most cellular plans or hotspot WiFi connections.
      */
-    private static boolean isNetworkAvailableForUpdate(Context context) {
+    private static int getNetworkState(Context context) {
         ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
 
-        // this could be cellular or wifi
         NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
-        if (activeNetwork == null) {
-            return false;
+        if (activeNetwork == null || !activeNetwork.isConnected()) {
+            return FLAG_NET_UNAVAILABLE;
         }
 
-        if (activeNetwork.getType() != ConnectivityManager.TYPE_WIFI && Preferences.get().isUpdateOnlyOnWifi()) {
-            Log.i(TAG, "Skipping update - wifi not available");
-            return false;
+        int networkType = activeNetwork.getType();
+        switch (networkType) {
+            case ConnectivityManager.TYPE_ETHERNET:
+            case ConnectivityManager.TYPE_WIFI:
+                if (Build.VERSION.SDK_INT >= 16 && cm.isActiveNetworkMetered()) {
+                    return FLAG_NET_METERED;
+                } else {
+                    return FLAG_NET_NO_LIMIT;
+                }
+            default:
+                return FLAG_NET_METERED;
         }
-        return activeNetwork.isConnectedOrConnecting();
+    }
+
+    /**
+     * In order to send a {@link Toast} from a {@link IntentService}, we have to do these tricks.
+     */
+    private void sendNoInternetToast() {
+        if (toastHandler == null) {
+            toastHandler = new Handler(Looper.getMainLooper());
+        }
+        toastHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                Toast.makeText(getApplicationContext(),
+                        R.string.warning_no_internet, Toast.LENGTH_SHORT).show();
+            }
+        });
     }
 
     @Override
@@ -315,9 +347,20 @@ public class UpdateService extends IntentService {
 
         try {
             // See if it's time to actually do anything yet...
+            int netState = getNetworkState(this);
+            if (netState == FLAG_NET_UNAVAILABLE) {
+                Utils.debugLog(TAG, "No internet, cannot update");
+                if (manualUpdate) {
+                    sendNoInternetToast();
+                }
+                return;
+            }
+
             if (manualUpdate) {
-                Utils.debugLog(TAG, "Unscheduled (manually requested) update");
-            } else if (!verifyIsTimeForScheduledRun()) {
+                Utils.debugLog(TAG, "manually requested update");
+            } else if (!verifyIsTimeForScheduledRun()
+                    || (netState == FLAG_NET_METERED && Preferences.get().isUpdateOnlyOnUnmeteredNetworks())) {
+                Utils.debugLog(TAG, "don't run update");
                 return;
             }
 
diff --git a/app/src/main/java/org/fdroid/fdroid/data/InstalledAppProviderService.java b/app/src/main/java/org/fdroid/fdroid/data/InstalledAppProviderService.java
index 74aeb18c4..34616230a 100644
--- a/app/src/main/java/org/fdroid/fdroid/data/InstalledAppProviderService.java
+++ b/app/src/main/java/org/fdroid/fdroid/data/InstalledAppProviderService.java
@@ -11,11 +11,13 @@ import android.net.Uri;
 import android.os.Process;
 import android.support.annotation.Nullable;
 
+import org.acra.ACRA;
 import org.fdroid.fdroid.Hasher;
 import org.fdroid.fdroid.Utils;
 import org.fdroid.fdroid.data.Schema.InstalledAppTable;
 
 import java.io.File;
+import java.io.FilenameFilter;
 import java.security.NoSuchAlgorithmException;
 import java.util.List;
 import java.util.Map;
@@ -154,24 +156,49 @@ public class InstalledAppProviderService extends IntentService {
     @Override
     protected void onHandleIntent(Intent intent) {
         Process.setThreadPriority(Process.THREAD_PRIORITY_LOWEST);
-        if (intent != null) {
-            String packageName = intent.getData().getSchemeSpecificPart();
-            final String action = intent.getAction();
-            if (ACTION_INSERT.equals(action)) {
-                PackageInfo packageInfo = getPackageInfo(intent, packageName);
-                if (packageInfo != null) {
-                    File apk = new File(packageInfo.applicationInfo.publicSourceDir);
-                    if (apk.exists() && apk.canRead()) {
+        if (intent == null) {
+            return;
+        }
+
+        String packageName = intent.getData().getSchemeSpecificPart();
+        final String action = intent.getAction();
+        if (ACTION_INSERT.equals(action)) {
+            PackageInfo packageInfo = getPackageInfo(intent, packageName);
+            if (packageInfo != null) {
+                File apk = new File(packageInfo.applicationInfo.publicSourceDir);
+                if (apk.isDirectory()) {
+                    FilenameFilter filter = new FilenameFilter() {
+                        @Override
+                        public boolean accept(File dir, String name) {
+                            return name.endsWith(".apk");
+                        }
+                    };
+                    File[] files = apk.listFiles(filter);
+                    if (files == null) {
+                        String msg = packageName + " sourceDir has no APKs: "
+                                + apk.getAbsolutePath();
+                        Utils.debugLog(TAG, msg);
+                        ACRA.getErrorReporter().handleException(new IllegalArgumentException(msg), false);
+                        return;
+                    }
+                    apk = files[0];
+                }
+                if (apk.exists() && apk.canRead()) {
+                    try {
                         String hashType = "sha256";
                         String hash = Utils.getBinaryHash(apk, hashType);
                         insertAppIntoDb(this, packageInfo, hashType, hash);
+                    } catch (IllegalArgumentException e) {
+                        Utils.debugLog(TAG, e.getMessage());
+                        ACRA.getErrorReporter().handleException(e, false);
+                        return;
                     }
                 }
-            } else if (ACTION_DELETE.equals(action)) {
-                deleteAppFromDb(this, packageName);
             }
-            notifyEvents.onNext(null);
+        } else if (ACTION_DELETE.equals(action)) {
+            deleteAppFromDb(this, packageName);
         }
+        notifyEvents.onNext(null);
     }
 
     /**
diff --git a/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java b/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java
index 04bf202fa..d792ed2b0 100644
--- a/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java
+++ b/app/src/main/java/org/fdroid/fdroid/net/HttpDownloader.java
@@ -3,6 +3,7 @@ package org.fdroid.fdroid.net;
 import com.nostra13.universalimageloader.core.download.BaseImageDownloader;
 
 import org.apache.commons.io.FileUtils;
+import org.fdroid.fdroid.BuildConfig;
 import org.fdroid.fdroid.FDroidApp;
 import org.fdroid.fdroid.Utils;
 import org.spongycastle.util.encoders.Base64;
@@ -83,6 +84,7 @@ public class HttpDownloader extends Downloader {
 
         // get the file size from the server
         HttpURLConnection tmpConn = getConnection();
+        tmpConn.setRequestMethod("HEAD");
         int contentLength = -1;
         if (tmpConn.getResponseCode() == 200) {
             contentLength = tmpConn.getContentLength();
@@ -115,6 +117,8 @@ public class HttpDownloader extends Downloader {
             connection = NetCipher.getHttpURLConnection(sourceUrl);
         }
 
+        connection.setRequestProperty("User-Agent", "F-Droid " + BuildConfig.VERSION_NAME);
+
         if (username != null && password != null) {
             // add authorization header from username / password if set
             String authString = username + ":" + password;
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index d23295a97..fdb4542a8 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -21,7 +21,7 @@
     <string name="update_interval">Automatic update interval</string>
     <string name="update_interval_zero">No automatic app list updates</string>
     <string name="automatic_scan_wifi">Only on Wi-Fi</string>
-    <string name="automatic_scan_wifi_on">Update app lists automatically only on Wi-Fi</string>
+    <string name="automatic_scan_wifi_on">Only update automatically on unmetered networks like Wi-Fi</string>
     <string name="update_auto_download">Automatically download updates</string>
     <string name="update_auto_download_summary">Download the update files in the background</string>
     <string name="update_auto_install">Automatically install updates</string>
@@ -201,6 +201,7 @@
     <string name="repos_unchanged">All repositories are up to date</string>
         <string name="all_other_repos_fine">All other repos didn\'t create errors.</string>
         <string name="global_error_updating_repos">Error during update: %s</string>
+    <string name="warning_no_internet">Cannot update, are you connected to the internet?</string>
     <string name="no_permissions">No permissions are used.</string>
     <string name="permissions">Permissions</string>
     <string name="no_handler_app">You don\'t have any available app that can handle %s.</string>