This is actually caused by a slight Access Control bug.
Access Control hooks the WordPress get_page() function during plugin load. Unfortunately it calls the pluggable function is_user_logged_in() which means it will crash WordPress if any other plugin calls this function after during plugin load.
Code from wordpress-access-control.php.
add_filter( 'get_pages', array( 'WordPressAccessControl', 'get_pages' ) );
...
class WordPressAccessControl
{
...
function get_pages( $pages )
{
// Don't affect the display of pages when viewing the list in the admin
if ( is_admin() ) {
return $pages;
}
// Whether or not the user is logged in
$auth = is_user_logged_in();
...
}
...
}
The ideal solution is to obtain the user id without using the pluggable functions and apply this hook before the plugins load but this isn’t so easy (try following the trail in pluggable.php).
A less perfect solution is to forgo the filtering of the pages during plugin load and apply the action hook at high priority at the action hook ‘init’ which occurs after pluggables have been loaded and the user has been authenticated as follows.
New code (NB delete old get_pages filter)
add_action( 'init', array( 'WordPressAccessControl', 'add_get_page_hook' ), 0 );
class WordPressAccessControl
{
...
function add_get_page_hook()
{
add_filter( 'get_pages', array( 'WordPressAccessControl', 'get_pages' ) );
}
...
}
However there is the slight risk that other plugins with this hook at priority 0 that use get_page will miss out. You can use the following code to remove that possibility but no guarantees it will be future proof. It simply does what $wp->init() does in wp-settings.php a little bit earlier to no ill effect.
New code (NB delete old get_pages filter)
add_action( 'after_setup_theme', array( 'WordPressAccessControl', 'add_get_page_hook' ), 0 );
class WordPressAccessControl
{
...
function add_get_page_hook()
{
wp_get_current_user();
add_filter( 'get_pages', array( 'WordPressAccessControl', 'get_pages' ) );
}
...
}
As far as I can see this is the only Access Control hook that has this problem.
As to other plugins that cause this problem the one that has the most reports is WP User Frontend Version 1.1 but there is a new development version of this that fixes the problem.
Cheers
TheProfessor
