@pascal.fragnoud
The goal of the OP was to reconfigure tags and remove a udt param that was added. For v8+ you would use system.tag.configure. However, you first need the configuration of the tags to reconfigure, which is where getConfiguration comes in. However, using getConfiguration on a udt instance will not just get you the config of the non-defaults configured on the instance (eg like when you copy json of the UDT instance in the tag browser), it will return the non-defaults on the UDT instance and also that are configured in the edit definition as well. If you then use this return in configure, then you'll end up adding property overrides to the tags in the instance for any non default tag config set in the UDT definition, effectively decoupling the UDT instance from the definition and destroying it.