Misleading error message for non-existent plugin settings page

[Latz]

If you call a plugin settings page that does not exist
(e.g. ​http://.../wp-admin/options-general.php?page=not-here) WordPress dies with the error message "You do not have sufficient permissions to access this page." though the user would have the permissions if the page would exist.

Quite confusing. Happened to me as an author changed the $menu_slug in an update and I tried to load the option page via my browser's bookmark. Took me some time to figure out what the problem was.

The error message should be "Plugin setting page does not exist."

[SergeyBiryukov]

#14060