Drupal 'Access Denied' on all pages
Ran into an interesting little snag this morning - a client's Drupal site was spitting out "Access Denied" errors for all page loads by anonymous users. It didn't appear to be a permissions problem - the nodes just wouldn't let anyone look at them.
A bit of Googling found a bunch of posts like this that say that, for some mysterious reason, Drupal can lose the contents of the node_access table and you need to repopulate them.
INSERT INTO node_access (nid ,gid ,realm ,grant_view, grant_update , grant_delete) VALUES ( '0', '0', 'all', '1', '0', '0')
Unfortunately, I didn't exactly have access to the client's database. A bit of poking around in the source showed me that visiting /admin/content/node-settings/rebuild would fire off an internal process to do the same thing.
Crisis averted, fix discovered. I just hope I don't need to use it again in the future.