I have never had issues with updating Slimstat - we have full version and paid for everything.
Just going up one version of Slimstat and everytime we load the upgrade we have to go back down getting
Fatal error: Access to undeclared static property: wp_slimstat::$update_checker in E:xampphtdocshomewp-contentpluginswp-slimstat-custom-dbindex.php on line 18
Crashes the server immediately on update.