Symfony $ form-> createView会在浏览器中导致错误代码：ERR_EMPTY_RESPONSE

Our controller method creates a form object and passes $form->createView() to the view data. Monolog captures a few debug messages, but no error or response is produced.

We are using symfony 2.3.12.

The problem does not occur on my local MAMP environment but does occur on a vagrant box, and our production/staging servers.

My guess is it's something specific with our environments but I'm hoping someone has experienced and solved this before.

Also this gist includes the controller, a model object and FormType. https://gist.github.com/jeremymoore/453edcdbc3236f8e25b8

Any ideas?

dev.log or prod.log looks like this:

[2014-04-23 15:13:04] request.INFO: Matched route "ir_compare_select" (parameters: "_controller": "IR\CameraBundle\Controller\CompareController::irCompareAction", "_route": "ir_compare_select") [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.request" to listener "Symfony\Component\HttpKernel\EventListener\LocaleListener::onKernelRequest". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.request" to listener "Symfony\Component\Security\Http\Firewall::onKernelRequest". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.request" to listener "Symfony\Component\HttpKernel\EventListener\ErrorsLoggerListener::injectLogger". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.request" to listener "Symfony\Component\HttpKernel\EventListener\ErrorsLoggerListener::injectLogger". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.controller" to listener "Symfony\Bundle\FrameworkBundle\DataCollector\RouterDataCollector::onKernelController". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.controller" to listener "Symfony\Component\HttpKernel\DataCollector\RequestDataCollector::onKernelController". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.controller" to listener "Sensio\Bundle\FrameworkExtraBundle\EventListener\ControllerListener::onKernelController". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.controller" to listener "Sensio\Bundle\FrameworkExtraBundle\EventListener\ParamConverterListener::onKernelController". [] []
[2014-04-23 15:13:04] event.DEBUG: Notified event "kernel.controller" to listener "Sensio\Bundle\FrameworkExtraBundle\EventListener\TemplateListener::onKernelController". [] []

Error message seen in Chrome: other browsers show similar messages