diff --git a/src/CoreBundle/EventSubscriber/LocaleSubscriber.php b/src/CoreBundle/EventSubscriber/LocaleSubscriber.php
index 7922a393d1e..79ed6f71d90 100644
--- a/src/CoreBundle/EventSubscriber/LocaleSubscriber.php
+++ b/src/CoreBundle/EventSubscriber/LocaleSubscriber.php
@@ -9,6 +9,7 @@
 use Chamilo\CoreBundle\Entity\Course;
 use Chamilo\CoreBundle\Settings\SettingsManager;
 use Chamilo\CourseBundle\Settings\SettingsCourseManager;
+use Doctrine\ORM\EntityManagerInterface;
 use Symfony\Component\DependencyInjection\ParameterBag\ParameterBagInterface;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\HttpFoundation\Request;
@@ -24,95 +25,119 @@ public function __construct(
         private string $defaultLocale,
         private SettingsManager $settingsManager,
         private ParameterBagInterface $parameterBag,
-        private SettingsCourseManager $courseSettingsManager
+        private SettingsCourseManager $courseSettingsManager,
+        private EntityManagerInterface $em,
     ) {}
 
     public function onKernelRequest(RequestEvent $event): void
     {
         $request = $event->getRequest();
 
+        // Skip if not installed or no session is available
         $installed = $this->parameterBag->has('installed') && 1 === (int) $this->parameterBag->get('installed');
         if (!$installed || !$request->hasSession()) {
             return;
         }
 
-        $sessionHandler = $request->getSession();
+        $session = $request->getSession();
 
-        // Override locale if forced via ?_locale=xx
-        if ($attrLocale = $request->query->get('_locale')) {
-            $sessionHandler->set('_selected_locale', $attrLocale);
+        // Honor explicit override via ?_locale=xx (persist for later requests)
+        if ($queryLocale = $request->query->get('_locale')) {
+            $session->set('_selected_locale', $queryLocale);
         }
 
-        // Determine locale based on priority logic
+        // Resolve locale and apply
         $locale = $this->getCurrentLanguage($request);
-
-        // Apply locale to request and session
         $request->setLocale($locale);
-        $sessionHandler->set('_locale', $locale);
+        $session->set('_locale', $locale);
     }
 
     public function getCurrentLanguage(Request $request): string
     {
-        $sessionHandler = $request->getSession();
+        $session = $request->getSession();
         $localeList = [];
 
-        // 1. Platform default locale
+        // 1) Platform default
         if ($platformLocale = $this->settingsManager->getSetting('language.platform_language')) {
             $localeList['platform_lang'] = $platformLocale;
         }
 
-        // 2. User profile locale from session
-        if ($userLocale = $sessionHandler->get('_locale_user')) {
+        // 2) User profile (from session)
+        if ($userLocale = $session->get('_locale_user')) {
             $localeList['user_profil_lang'] = $userLocale;
         }
 
-        // 3. Course locale or user locale if course allows user language
-        $course = $sessionHandler->get('course');
+        // 3) Course language, or user language if course allows it
+        // First try: course already in session
+        $course = $session->get('course');
+
+        // Fallback: resolve course from request if not in session yet
+        if (!$course instanceof Course) {
+            // Accept both numeric id (?cid=123) and code (?cid=ABC) as well as legacy ?cidReq=CODE
+            $cid   = $request->query->get('cid');
+            $cidReq = $request->query->get('cidReq');
+
+            if ($cid) {
+                if (ctype_digit((string) $cid)) {
+                    $course = $this->em->getRepository(Course::class)->find((int) $cid);
+                } else {
+                    $course = $this->em->getRepository(Course::class)->findOneBy(['code' => (string) $cid]);
+                }
+            }
+
+            if (!$course && $cidReq) {
+                $course = $this->em->getRepository(Course::class)->findOneBy(['code' => (string) $cidReq]);
+            }
+        }
+
         if ($course instanceof Course) {
-            $userLocale = $localeList['user_profil_lang'] ?? null;
+            $userLocale   = $localeList['user_profil_lang'] ?? null;
             $courseLocale = $course->getCourseLanguage();
 
+            // The per-course setting decides whether to use user language
             $this->courseSettingsManager->setCourse($course);
-            if ('1' === $this->courseSettingsManager->getCourseSettingValue('show_course_in_user_language') && $userLocale) {
+            $allowUser = $this->courseSettingsManager->getCourseSettingValue('show_course_in_user_language') === '1';
+
+            if ($allowUser && $userLocale) {
                 $localeList['course_lang'] = $userLocale;
             } elseif ($courseLocale) {
                 $localeList['course_lang'] = $courseLocale;
             }
         }
 
-        // 4. Locale selected manually via URL
-        if ($localeFromUrl = $sessionHandler->get('_selected_locale')) {
-            $localeList['user_selected_lang'] = $localeFromUrl;
+        // 4) Explicit selection via URL (?_locale=xx) saved earlier in session
+        if ($selected = $session->get('_selected_locale')) {
+            $localeList['user_selected_lang'] = $selected;
         }
 
-        // 5. Resolve locale based on configured language priorities
+        // 5) Honor configured priorities language_priority_1..4
         foreach ([
-            'language_priority_1',
-            'language_priority_2',
-            'language_priority_3',
-            'language_priority_4',
-        ] as $settingKey) {
+                     'language_priority_1',
+                     'language_priority_2',
+                     'language_priority_3',
+                     'language_priority_4',
+                 ] as $settingKey) {
             $priority = $this->settingsManager->getSetting("language.$settingKey");
             if (!empty($priority) && !empty($localeList[$priority])) {
                 return $localeList[$priority];
             }
         }
 
-        // 6. Fallback order if priorities are not defined
+        // 6) Fallback order when priorities are absent
         foreach (['platform_lang', 'user_profil_lang', 'course_lang', 'user_selected_lang'] as $key) {
             if (!empty($localeList[$key])) {
                 return $localeList[$key];
             }
         }
 
-        // 7. Final fallback to system default
+        // 7) Final fallback to system default
         return $this->defaultLocale;
     }
 
     public static function getSubscribedEvents(): array
     {
         return [
-            // must be registered before the default Locale listener
+            // Must run before Symfony's default Locale listener
             KernelEvents::REQUEST => [['onKernelRequest', 20]],
         ];
     }