I updated wordpress to 4.2.2 and popup pro seems to now break the site: http://babyprocar.com/
If I disable the plugin the site works.
We had both the free and pro version of popup plugin installed (only 1 active) the non pro version doesnt break the site but doesnt have the functionality we need.
In the php error log I can see this error:
[Wed Jun 10 21:46:24.140968 2015] [:error] [pid 1586] [client 126.96.36.199:59027] PHP Warning: Missing argument 2 for apply_filters(), called in /home/babyprocar/public_html/wp-content/plugins/popover/inc/rules/class-popup-rule-protectedcontent.php on line 59 and defined in /home/babyprocar/public_html/wp-includes/plugin.php on line 177
[Wed Jun 10 21:46:24.155935 2015] [:error] [pid 1586] [client 188.8.131.52:59027] PHP Fatal error: Cannot use object of type WP_Error as array in /home/babyprocar/public_html/wp-includes/functions.php on line 3198