On Debian and Ubuntu servers, PHP keeps sessions in a folder the web server cannot list, and a system cron job deletes old ones. Magpie now leaves that cleanup to the cron job instead of attempting it on requests, so the log no longer fills with "ps_files_cleanup_dir: Permission denied" warnings.
Session cleanup left to the server's own job
Magpie no longer tries to tidy old sessions on page requests where the server cleans them on a schedule, which stops a repeated permission warning in the log.