recover-session() in lisp/files.el says: (if (null auto-save-list-file-prefix) (error "You set `auto-save-list-file-prefix' to disable making session files")) However, (setq auto-save-list-file-prefix nil) does not means to disable session files :-) You can easily check why. normal-top-level() in lisp/startup.el says: ;; Specify the file for recording all the auto save files of ;; this session. This is used by recover-session. (setq auto-save-list-file-name (expand-file-name (format "%s%d-%s" auto-save-list-file-prefix (emacs-pid) (system-name)))) Hahaha, there are NO CHECKS whether auto-save-list-file-prefix is nil or not, so, auto-save-list-file-name will be "nil-PID-SYSTEMNAME" if you setq auto-save-list-file-prefix to nil. See how the FSF Emacs do if this behavior comes from FSF Emacs. Changes in May/01/1998 about lisp/files.el does not consider about this, doesn't it? Sorry no patches, but maybe easy to change. -- - Makoto `MAR' MATSUSHITA