I looked in my nginx error.log and saw that it is overfilled with these errors:
FastCGI sent in stderr: "PHP message:" while reading response header from upstream, client: ..., server: ..., request: "GET /forum HTTP/1.1", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "...", referrer: "..."
As you can see there is no message where the error is thrown.
What is the reason why no message is shown there?
Thank you in advance.