diff --git a/app/src/main/java/org/digitalcampus/oppia/activity/OfflineCourseImportActivity.java b/app/src/main/java/org/digitalcampus/oppia/activity/OfflineCourseImportActivity.java
index f97d4e0b5..fd7416b3e 100644
--- a/app/src/main/java/org/digitalcampus/oppia/activity/OfflineCourseImportActivity.java
+++ b/app/src/main/java/org/digitalcampus/oppia/activity/OfflineCourseImportActivity.java
@@ -1,14 +1,12 @@
 package org.digitalcampus.oppia.activity;
 
-import static android.Manifest.permission.READ_EXTERNAL_STORAGE;
-
 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.ClipData;
 import android.content.Intent;
-import android.content.pm.PackageManager;
 import android.database.Cursor;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.provider.OpenableColumns;
@@ -19,13 +17,13 @@
 
 import androidx.activity.result.ActivityResultLauncher;
 import androidx.activity.result.contract.ActivityResultContracts;
-import androidx.core.app.ActivityCompat;
-import androidx.core.content.ContextCompat;
+import androidx.annotation.NonNull;
 
 import org.apache.commons.io.IOUtils;
 import org.digitalcampus.mobile.learning.R;
 import org.digitalcampus.mobile.learning.databinding.ActivityOfflineCourseImportBinding;
 import org.digitalcampus.oppia.adapter.OfflineCourseImportAdapter;
+import org.digitalcampus.oppia.application.PermissionsManager;
 import org.digitalcampus.oppia.exception.CourseInstallException;
 import org.digitalcampus.oppia.listener.InstallCourseListener;
 import org.digitalcampus.oppia.listener.OnRemoveButtonClickListener;
@@ -55,7 +53,6 @@
 
 public class OfflineCourseImportActivity extends AppActivity implements InstallCourseListener, ScanMediaListener, OnRemoveButtonClickListener {
 
-    private static final int REQUEST_PERMISSION_READ_EXTERNAL_STORAGE = 1;
     private ActivityOfflineCourseImportBinding binding;
     private OfflineCourseImportAdapter adapter;
     private boolean coursesImported = false;
@@ -104,8 +101,10 @@ public boolean onOptionsItemSelected(MenuItem item) {
     }
 
     private void launchFileExplorer() {
-        if (ContextCompat.checkSelfPermission(this, READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
-            ActivityCompat.requestPermissions(this, new String[]{READ_EXTERNAL_STORAGE}, REQUEST_PERMISSION_READ_EXTERNAL_STORAGE);
+        final List<String> notGrantedPerms = PermissionsManager.filterNotGrantedPermissions(
+                OfflineCourseImportActivity.this, PermissionsManager.OFFLINE_COURSE_IMPORT_PERMISSIONS_REQUIRED);
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU && !notGrantedPerms.isEmpty()) {
+            PermissionsManager.requestPermissions(OfflineCourseImportActivity.this, notGrantedPerms);
         } else {
             Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
             intent.addCategory(Intent.CATEGORY_OPENABLE);
@@ -115,6 +114,12 @@ private void launchFileExplorer() {
         }
     }
 
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
+        PermissionsManager.onRequestPermissionsResult(this, requestCode, permissions, grantResults);
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+    }
+
     private final ActivityResultLauncher<Intent> someActivityResultLauncher = registerForActivityResult(
             new ActivityResultContracts.StartActivityForResult(),
             result -> {
diff --git a/app/src/main/java/org/digitalcampus/oppia/application/PermissionsManager.java b/app/src/main/java/org/digitalcampus/oppia/application/PermissionsManager.java
index b047db81d..6f9866658 100644
--- a/app/src/main/java/org/digitalcampus/oppia/application/PermissionsManager.java
+++ b/app/src/main/java/org/digitalcampus/oppia/application/PermissionsManager.java
@@ -19,24 +19,29 @@
 
 import android.Manifest;
 import android.app.Activity;
+import android.app.AlertDialog;
 import android.content.Context;
+import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
+import android.net.Uri;
 import android.os.Build;
-
-import androidx.annotation.NonNull;
-import androidx.preference.PreferenceManager;
-
+import android.provider.Settings;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.core.app.ActivityCompat;
+import androidx.preference.PreferenceManager;
+
 import org.digitalcampus.mobile.learning.R;
 import org.digitalcampus.mobile.learning.databinding.ViewPermissionsExplanationBinding;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 public class PermissionsManager {
@@ -59,6 +64,10 @@ public class PermissionsManager {
             Manifest.permission.POST_NOTIFICATIONS
     );
 
+    public static final List<String> OFFLINE_COURSE_IMPORT_PERMISSIONS_REQUIRED = Arrays.asList(
+            Manifest.permission.READ_EXTERNAL_STORAGE
+    );
+
     public static final int STARTUP_PERMISSIONS = 1;
     public static final int BLUETOOTH_PERMISSIONS = 2;
     public static final int STORAGE_PERMISSIONS = 3;
@@ -76,6 +85,14 @@ private static void setAsked(SharedPreferences prefs, String permission) {
         prefs.edit().putBoolean(permission + "_asked", true).apply();
     }
 
+    private static boolean isPermissionDeniedOnce(SharedPreferences prefs, String permission) {
+        return prefs.getBoolean(permission + "_denied", false);
+    }
+
+    private static void setDenied(SharedPreferences prefs, String permission) {
+        prefs.edit().putBoolean(permission + "_denied", true).apply();
+    }
+
     public static boolean checkPermissionsAndInform(final Activity act, int perms) {
         ViewGroup container = act.findViewById(R.id.permissions_explanation);
         return checkPermissionsAndInform(act, perms, container);
@@ -151,6 +168,10 @@ private static void showPermissionDescriptions(Context ctx, View container, fina
         }
     }
 
+    public static void requestPermission(final Activity act, String permission) {
+        requestPermissions(act, Collections.singletonList(permission));
+    }
+
     public static void requestPermissions(final Activity act, List<String> permissions) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             act.requestPermissions(permissions.toArray(new String[0]), PERMISSIONS_REQUEST);
@@ -203,15 +224,39 @@ public static boolean onRequestPermissionsResult(Context ctx, int requestCode, S
             for (int i = 0; i < permissions.length; i++) {
                 setAsked(prefs, permissions[i]);
 
-                if (grantResults[i] == PackageManager.PERMISSION_GRANTED) {
+                if (grantResults.length > 0 && grantResults[i] == PackageManager.PERMISSION_GRANTED) {
                     Log.d("Permissions", "Permission Granted: " + permissions[i]);
                     permissionsGranted++;
-                } else if (grantResults[i] == PackageManager.PERMISSION_DENIED) {
+                } else {
                     Log.d("Permissions", "Permission Denied: " + permissions[i]);
+                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                        if (ActivityCompat.shouldShowRequestPermissionRationale((Activity) ctx, permissions[i])) {
+                            setDenied(prefs, permissions[i]);
+                        } else if (isPermissionDeniedOnce(prefs, permissions[i])) {
+                            showPermissionDeniedDialog(ctx);
+                        }
+                    }
                 }
             }
         }
         return permissions.length == permissionsGranted;
     }
 
+    public static void showPermissionDeniedDialog(Context context) {
+        AlertDialog.Builder builder = new AlertDialog.Builder(context);
+        builder.setTitle(context.getString(R.string.permissions_denied));
+        builder.setMessage(context.getString(R.string.permissions_not_askable_message));
+        builder.setPositiveButton(context.getString(R.string.app_settings), (dialog, which) -> PermissionsManager.openAppSettings(context));
+        builder.setNegativeButton(context.getString(R.string.cancel), (dialog, which) -> {});
+
+        builder.create().show();
+    }
+
+    public static void openAppSettings(Context context) {
+        Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
+        Uri uri = Uri.fromParts("package", context.getPackageName(), null);
+        intent.setData(uri);
+        context.startActivity(intent);
+    }
+
 }
diff --git a/app/src/main/java/org/digitalcampus/oppia/utils/storage/FileUtils.java b/app/src/main/java/org/digitalcampus/oppia/utils/storage/FileUtils.java
index 3e0dc3a2d..aa8741245 100644
--- a/app/src/main/java/org/digitalcampus/oppia/utils/storage/FileUtils.java
+++ b/app/src/main/java/org/digitalcampus/oppia/utils/storage/FileUtils.java
@@ -87,11 +87,18 @@ public static void unzipFiles(Context context, String srcDirectory, String srcFi
 
         long availableStorage = Storage.getAvailableStorageSize(context);
         long uncompressedSize = 0;
-        try (ZipFile zipFile = new ZipFile(sourceFile)) {
-            Enumeration<? extends ZipEntry> entries = zipFile.entries();
-            while (entries.hasMoreElements()) {
-                ZipEntry zipEntry = entries.nextElement();
-                uncompressedSize += zipEntry.getSize();
+        try (ZipInputStream zipInputStream = new ZipInputStream(new FileInputStream(sourceFile))) {
+            byte[] buffer = new byte[4096];
+            ZipEntry zipEntry;
+
+            while ((zipEntry = zipInputStream.getNextEntry()) != null) {
+                if (!zipEntry.isDirectory()) {
+                    int bytesRead;
+                    while ((bytesRead = zipInputStream.read(buffer)) != -1) {
+                        uncompressedSize += bytesRead;
+                    }
+                }
+                zipInputStream.closeEntry();
             }
         } catch (IOException e) {
             e.printStackTrace();
diff --git a/app/src/main/res/values-es/strings.xml b/app/src/main/res/values-es/strings.xml
index afc3448fe..666ff225e 100644
--- a/app/src/main/res/values-es/strings.xml
+++ b/app/src/main/res/values-es/strings.xml
@@ -280,7 +280,7 @@
     <string name="error_preloading_accounts">Error precargando cuentas de usuario desde fichero CSV</string>
     <string name="error_reset_password">Nombre de usuario o email no encontrado\nInténtelo de nuevo</string>
     <string name="no_title_set">Sin título</string>
-    h
+
     <string name="info.startup.preloaded_accounts">Precargadas %1$d nueva(s) cuenta(s) de usuario.</string>
     <string name="empty_state_media">Genial! Ha descargado todo el contenido multimedia de sus cursos en el dispositivo.</string>
     <string name="menu_sort_by">Ordenar por</string>
@@ -305,6 +305,8 @@
     <string name="permissions.bluetooth.message">La app necesita permisos adicionales para buscar otros dispositivos Bluetooth.</string>
     <string name="permissions.location.title">acceder a la ubicación</string>
     <string name="permissions.location.description">En las últimas versiones de Android se necesita este permiso para poder enlazar otros dispositivos con Bluetooth</string>
+    <string name="permissions.denied">Permiso denegado</string>
+    <string name="app_settings">Ajustes de la app</string>
 
     <string name="prefLogoutEnabled">Permitir cierre de sesión desde el menú principal</string>
     <string name="register_alert_title">Registro</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 1a9de99e9..505c4b0a9 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -368,6 +368,7 @@
         needs the following permissions to function properly:</string>
     <string name="permissions.storage.title">Read and modify contents of the SD card</string>
     <string name="permissions.simple.title">Permissions needed</string>
+    <string name="permissions.denied">Permission denied</string>
     <string name="permissions.storage.description">&appName; needs access to the SD card to be able to store the downloaded media contents for the courses</string>
     <string name="permissions.phone_state.title">read phone state and identity</string>
     <string name="permissions.phone_state.description">&appName; needs access to the phone identity to get information about your device model and Android version</string>
@@ -377,6 +378,7 @@
     <string name="permissions.not_askable.info">You see this message because permissions were prompted before and you denied them and checked \"Don\'t ask again\"</string>
     <string name="permissions.bluetooth.message">The app needs some additional permissions to scan for Bluetooth devices.</string>
     <string name="error_apikey_expired">Your API key expired. Please, log in again.</string>
+    <string name="app_settings">App Settings</string>
 
     <string name="privacy.title">Privacy and Your Data</string>
     <string name="privacy.policy_info">Privacy policy</string>