Hi, The annoying mixed installation problems keep popping up in the mailing list and other communication channels. The attached is a patch trying to forbid loading multiple Org versions. The idea is putting a macro that internally expands Org git version at compile time and later compares the expanded value with the runtime value. Comments? Alternative ideas? In the past we also discussed checking load-history, but I am afraid that it will spoil the loading time. load-history can get quite large. Also, I was thinking about using (provide 'library '(version-subfeature)) but I have no idea how to do it automatically. The proposed patch only requires adding two lines to newly added Org libraries in future. Otherwise, it should just work. Best, Ihor