diff --git a/scripts/upgrade b/scripts/upgrade
index 2dde7ab..f29f28d 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -112,6 +112,17 @@ ynh_add_fpm_config
 
 #=================================================
 # SPECIFIC UPGRADE
+#=================================================
+# DEACTIVATE DEBUG MODE
+#=================================================
+
+ynh_replace_string --match_string="defined('YII_DEBUG') or define('YII_DEBUG', true);"\
+ --replace_string="// defined('YII_DEBUG') or define('YII_DEBUG', true);"\
+ --target_file="$final_path/index.php"
+ynh_replace_string --match_string="defined('YII_ENV') or define('YII_ENV', 'dev');"\
+ --replace_string="// defined('YII_ENV') or define('YII_ENV', 'dev');"\
+ --target_file="$final_path/index.php"
+
 #=================================================
 # MIGRATE DATABASE
 #=================================================