diff --git a/scripts/change_url b/scripts/change_url
index 4775517..bcf134d 100644
--- a/scripts/change_url
+++ b/scripts/change_url
@@ -90,9 +90,31 @@ fi
 #=================================================
 # SPECIFIC MODIFICATIONS
 #=================================================
-# ...
+# STOP SERVICE
 #=================================================
 
+ynh_systemd_action --action=stop --service_name=$app
+
+#=================================================
+# MODIFY A CONFIG FILE
+#=================================================
+
+# Change the URL in the configuration file
+ynh_replace_string "EXTERNAL_URL=.*" "EXTERNAL_URL=https://$new_domain$new_path" "$final_path/.env"
+
+### Verify the checksum of a file, stored by `ynh_store_file_checksum` in the install script.
+### And create a backup of this file if the checksum is different. So the file will be backed up if the admin had modified it.
+ynh_backup_if_checksum_is_different "$final_path/.env"
+# Recalculate and store the checksum of the file for the next upgrade.
+ynh_store_file_checksum "$final_path/.env"
+
+#=================================================
+# START SERVICE
+#=================================================
+
+ynh_systemd_action --action=start --service_name=$app
+
+
 #=================================================
 # GENERIC FINALISATION
 #=================================================