Whenever I activate this plugin, it kicks me out of the dashboard. When I try to log back in, I get a “Sorry, you are not allowed to access this page.” error. I then have to go into the FTP and change the name of this plugin’s folder before it will let me back in.
I can’t find any other plugins that will let me delete posts from multiple categories after x-number of days.
Did you try to disable all other plugins ? So just enable the auto prune posts plugin to see if it is really this one?
I am asking because I have the plugin running on mulitple sites that I own, non of those report this error. So .. therefore it must be some sort of conflict with another plugin or perhaps your theme.