Installing and upgrading help

Hi everyone,

I am currently movi,g my Moodle from 2.4 to 3.0 and I get an error code saying that this function is deprecated.

The code deprecated is in renderers.php :

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$branch = $menu->add(get_string('my', 'theme_enfa'), new moodle_url('/my'), null, 10000);
   
        $categorytree = get_course_category_tree();
   
        foreach ($categorytree as $category)
        {
            $branch = $menu->add($category->name, new moodle_url('/course/category.php', array('id' =>  $category->id)));
               
            if (!empty($category->categories))
            {
                foreach ($category->categories as $subcategory)
                {
                    $this->add_category_to_custommenu($branch, $subcategory);
                }
            }
   
            if (!empty($category->courses))
            {
                foreach ($category->courses as $course)
                {
                    $branch->add($course->shortname, new moodle_url('/course/view.php', array('id' => $course->id)), $course->shortname);
                }
            }
   
        } // End foreach ($categorytree as $category)

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So I googled it and the only solution I found was : " Add $courses = get_course($categoryid) to your code"

But I'm not a PHP developper so I don't know how to use this function in my .php.

Have you a solution, a tip ?

Thank you for reading, and sorry if my English is not good.

Have a nice day !