diff --git a/course/format/classes/base.php b/course/format/classes/base.php
index 644a8b5d72f..6b658fa32fd 100644
--- a/course/format/classes/base.php
+++ b/course/format/classes/base.php
@@ -226,6 +226,18 @@ abstract class base {
             self::$instances = array();
         }
     }
+    /**
+     * Reset the current user for all courses.
+     *
+     * The course format cache resets every time the course cache resets but
+     * also when the user changes their language, all course editors
+     *
+     * @return void
+     */
+    public static function session_cache_reset_all(): void {
+        $statecache = cache::make('core', 'courseeditorstate');
+        $statecache->purge();
+    }
 
     /**
      * Reset the current user course format cache.
diff --git a/course/format/tests/behat/courseindex_language.feature b/course/format/tests/behat/courseindex_language.feature
new file mode 100644
index 00000000000..1f8af0ef955
--- /dev/null
+++ b/course/format/tests/behat/courseindex_language.feature
@@ -0,0 +1,36 @@
+@core @core_course @core_courseformat
+Feature: The course index language should change according to user preferences.
+  As a user in a course
+  I should see the same language in the course index and the course content when I switch languages.
+
+  Background:
+    Given remote langimport tests are enabled
+    Given the following "users" exist:
+      | username | firstname | lastname | email                |
+      | teacher1 | Teacher   | 1        | teacher1@example.com |
+      | student1 | Student   | 1        | student1@example.com |
+    And the following "course" exists:
+      | fullname         | Course 1 |
+      | shortname        | C1       |
+      | category         | 0        |
+      | enablecompletion | 1        |
+      | numsections      | 4        |
+    And the following "course enrolments" exist:
+      | user     | course | role           |
+      | student1 | C1     | student        |
+      | teacher1 | C1     | editingteacher |
+    And the following "language pack" exists:
+      | language | fr |
+    And I change window size to "large"
+
+  @javascript
+  Scenario Outline: Course index is refreshed when we change language.
+    Given I am on the "C1" "Course" page logged in as "<user>"
+    When I follow "Language" in the user menu
+    Then I should see "Language selector" user submenu
+    And I follow "Français ‎(fr)‎"
+    Then I should see "Généralités" in the "courseindex-content" "region"
+    Examples:
+      | user     |
+      | student1 |
+      | teacher1 |
diff --git a/lib/behat/classes/behat_core_generator.php b/lib/behat/classes/behat_core_generator.php
index 75e7860ef2c..2a81c598de1 100644
--- a/lib/behat/classes/behat_core_generator.php
+++ b/lib/behat/classes/behat_core_generator.php
@@ -259,6 +259,11 @@ class behat_core_generator extends behat_generator_base {
                 'datagenerator' => 'customlang',
                 'required' => ['component', 'stringid', 'value'],
             ],
+            'language packs' => [
+                'singular' => 'language pack',
+                'datagenerator' => 'langpack',
+                'required' => ['language'],
+            ],
             'analytics models' => [
                 'singular' => 'analytics model',
                 'datagenerator' => 'analytics_model',
@@ -549,6 +554,16 @@ class behat_core_generator extends behat_generator_base {
             tool_customlang_utils::checkin($USER->lang);
         }
     }
+    /**
+     * Imports a langpack.
+     *
+     * @param array $data
+     */
+    protected function process_langpack($data) {
+        $controller = new \tool_langimport\controller();
+        $controller->install_languagepacks($data['language']);
+        get_string_manager()->reset_caches();
+    }
 
     /**
      * Adapter to enrol_user() data generator.
diff --git a/lib/setup.php b/lib/setup.php
index ccbba5281d5..6c300f5ecc2 100644
--- a/lib/setup.php
+++ b/lib/setup.php
@@ -947,6 +947,7 @@ if (!isset($CFG->theme)) {
 if (isset($_GET['lang']) and ($lang = optional_param('lang', '', PARAM_SAFEDIR))) {
     if (get_string_manager()->translation_exists($lang, false)) {
         $SESSION->lang = $lang;
+        \core_courseformat\base::session_cache_reset_all();
     }
 }
 unset($lang);