in magento backend when i go to the manage feeds page it show 503 Service Unavailable error, and this error only comes on this page only, all other pages are working fine
here is the screenshot to see with page is showing error, and there is no maintenance.flag file
you need to check server or PHP error logs
the error should be logged there.
in server it show this error client denied by server configuration: public_html/app/etc/local.xml
and in magento log/system.log
Warning: strpos(): Empty needle in public_html/app/code/core/Zend/Controller/Request/Http.php on line 502