Magento add good feature In 22.214.171.124.
after magento upgrade or install security patches you got error on system > permission
there is variables and blocks they added for restriction,
if you got error here regarding tables missing then dont worry, you can download permission_block and permission_variables tables default structure and data from here.
For more detail follow this article.
Magento Missing Blocks
Hope it will help full to some one else.
I'm having this same problem but when I go to permissions>variables or blocks it pulls up a magento database error page. Any ideas or has anyone else had this problem?
wordpress/sidebar_widget_posts is the block name which should be white-listed.