I am looking for “on rename” event (server script ) code .
I don’t think this event exists. You will probably have to create another field old_name or something. Then compare the current name with the old name during the update event.
does renaming a doctype trigger the validate event ?
Renaming will call both
'after_rename'controller methods (assuming the DocType has them)
'validate'method is not called during a rename.