Obscure WordPress Errors – Why? Where? and How?

WordPress Error 1

‘You do not have sufficient permissions to access this page.’

This error is activated within the file wp-admin/menu.php which in turn gets included by wp-admin/admin.php which gets called by almost every WordPress administration page.

Here is a code snippet from wp-admin/menu.php where the error message is reported –

<?php
if (! user_can_access_admin_page()) {
      do_action('admin_page_access_denied');
      wp_die( __('You do not have sufficient permissions to access this page.') );
 }
?>

As you can see from the code snippet above, a good way to debug this error is by hooking into the admin_page_access_denied action in your plugin or your theme functions.php file.

<?php
add_action('admin_page_access_denied', 'debug_page_access');

function debug_page_access() {
	global $pagenow;
	global $menu;
	global $submenu;
	global $_wp_menu_nopriv;
	global $_wp_submenu_nopriv;
	global $plugin_page;
	global $_registered_pages;

	$parent = get_admin_page_parent();
	$hookname = get_plugin_page_hookname($plugin_page, $parent);

	echo "Pagenow = " . $pagenow . "<br/>";
	echo "Parent = " . $parent . "<br/>";
	echo "Hookname = " . $hookname . "<br/>";
	
	echo "Menu = " . $menu . "<br/>";
	echo "Submenu = " . $submenu[$parent] . "<br/>";
	echo "Menu nopriv = " . $_wp_menu_nopriv . "<br/>";
	echo "Submenu nopriv = " . $_wp_submenu_nopriv[$parent][$plugin_page] . "<br/>";
	echo "Plugin page = " . $plugin_page . "<br/>";
	echo "Registered pages = " . $_registered_pages[$hookname] . "<br/>";
	
}
?>

In the debug_page_access function we print out a series of global variables used in the user_can_access_admin_page check. By doing this, we can determine where the admin page failure is coming from.

The user_can_access_admin_page function is defined in wp-admin/includes/plugin.php.

WordPress Error 2

Are you sure you want to do this?

This error is the result of a WordPress nonce check failure.

In particular, this error is reported by the function wp_nonce_ays which is defined in wp-includes/functions.php.

The wp_nonce_ays function is called by the check_admin_referer function which appears everywhere within the WordPress administration areas (i.e. WordPress dashboard).

Below is the check_admin_referer source from the wp-includes/pluggable.php file.

<?php
function check_admin_referer($action = -1, $query_arg = '_wpnonce') {
	$adminurl = strtolower(admin_url());
	$referer = strtolower(wp_get_referer());
	$result = isset($_REQUEST[$query_arg]) ? wp_verify_nonce($_REQUEST[$query_arg], $action) : false;
	if ( !$result && !(-1 == $action && strpos($referer, $adminurl) !== false) ) {
		wp_nonce_ays($action);
		die();
	}
	do_action('check_admin_referer', $action, $result);
	return $result;
}endif;
?>

The function has three required conditions -

1. Line 5 – You must pass a nonce check.
2. Line 6 – You must pass the function an action.
3. Line 6 – The page (php file) calling the function (i.e., wp_get_referer) must be an administration url (as defined by the admin_url function). admin_url simply gets the administration path of the current blog – which can be the WordPress default (wp-admin) or which can be overridden by the admin_url filter.

The ‘Are you sure you want to do this?’ error comes from a failure in one of these areas.

WordPress Errors

These are the two most common errors I came across while writing plugins and themes in WordPress.

If you come across other obscure WordPress errors, please let me know and I will add it to the post.

Related Articles

<< Previous Next >>

add_menu_page, add_submenu_page

How to add navigation menus to the WordPress dashboard.

<< Previous Next >>

Expand the WordPress Media Library Admin Panel

How to add options to the WordPress Media Library panel. This tutorial was written based on WordPress 2.8. The same concepts will apply to WordPress 2.9, but some alterations are may be needed for handling new media actions.

<< Previous Next >>

Switch_Theme vs. Theme Switching

Theme Switching is the process of providing the ability for the user to change the presentation styles or look of your site with the use of a Theme Switcher. The process of changing your WordPress Theme by the site Administrator is not called theme switching. ~~[ WordPress Codex ] If we [...]

< Playback Stop Play >

add_menu_page, add_submenu_page

Expand the WordPress Media Library Admin Panel

Switch_Theme vs. Theme Switching