I have a website that has been setup and working fine for ages. It's built using Code Igniter. It's run using .htaccess files to restrict access and hide urls. All fine.
Until a couple of days ago when we try to access http://admin.dealersupport.co.uk we get a 500 error (this is the backend of the site, held in a separate subdomain.) Nothing else has changed on the server. I have tried restoring from a backup from when I know it was working. The problem persists.
The only thing I can think of is that we recently upgraded to Plesk 11.0.9 and since then we have been seeing some Apache instabilities.
The only thing that is thrown up by the error logs is this:
Wed Nov 21 08:40:17 2012] [error] [client 188.8.131.52] Options FollowSymLinks or SymLinksIfOwnerMatch is off which implies that RewriteRule directive is forbidden: /var/www/vhosts /dealersupport.co.uk/admin/index.pl, referer: http://admin.dealersupport.co.uk/login
I have now added this to my .htaccess files
Options +FollowSymLinks +SymLinksIfOwnerMatch RewriteEngine On
And that seems to have eliminated that error from the error logs, but we are still getting a 500 error when we have logged into the backend.