diff --git a/scripts/upgrade b/scripts/upgrade
index 407279ea..749b6aad 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -29,6 +29,11 @@ upgrade_type=$(ynh_check_app_version_changed)
 #=================================================
 ynh_script_progression --message="Ensuring downward compatibility..." --weight=1
 
+# If random_string doesn't exist, create it
+if [ -z "$random_string" ]; then
+    random_string="$(ynh_string_random --length=48)"
+    ynh_app_setting_set --app=$app --key=random_string --value=$random_string
+fi
 
 # If fpm_footprint doesn't exist, create it
 if [ -z "$fpm_footprint" ]; then