All Campaign namespace pages can't be saved at the moment on Commons, with the error message Value "cc-by-sa-4.0" not in enum for property cc-by-sa-3.0. I was able to reproduce locally too. I don't know yet why, but I'll find out.
Originally reported at https://commons.wikimedia.org/wiki/Commons:Village_pump#Incomprehensible_error_message_does_not_let_any_Campaign_edits by @Poco_a_poco.