We\'re developing a new site in Symfony. When Symfony encounters an error, such as a \"no route found\", and debug is set to true, it not only outputs a 404 code, it actually s
Under the monolog config in your config_dev.yml, remove the firephp/chromephp sections.
There is a bug report raised for this:
Issue 1695: Chrome needs option to turn off "Friendly 404" displays
According to the comments on that issue, if the server error page is more than 512 bytes, then it gets displayed correctly.
That said, I can't actually reproduce the problem, so I'm not sure if that workaround actually fixes it.