How can i find out why my php5-fpm failed to start?

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http://serverfault.com – i get 504 gateway timeout when i try to reach my server a small check didn't find any logs on php5-fpm logs, but just to make sure, i tried to restart it. when i'm trying to restart it: sudo service php5-fpm restart i get [fail] but when i do sudo service php5-fpm stop sudo service php5-fpm start I get no error. how can i investigate it if there are no logs? what can i do? (HowTos)