I am getting this message during startup of my Emacs, recently (since the update to Emacs 26?). I could not track down where is package is loaded and did not find anything related to this message in the web. It is not really a problem but I would like to know why my Emacs loads an obsolete package.
Add this to the top of your .emacs, you should get a backtrace when it loads:
(defun debug-on-load-obsolete (filename) (when (equal (car (last (split-string filename "[/\\]") 2)) "obsolete") (debug))) (add-to-list 'after-load-functions #'debug-on-load-obsolete)