Symfony2 app_dev.php仅出现错误500脚本过早结束

我对Symfony2有问题。一切都很好，有一天。。。开始解决问题。。。

当我打开一个页面时，我得到错误500。服务器返回此错误，而不是Symfony。如果我刷新，我显示显示页面没有错误。但当我打开一个新页面(新网址，同一网站(时，错误再次出现。

我尝试重新加载apache。我尝试删除缓存和日志中的所有内容。我的控制台文件、app.php文件、app_dev.php文件已取消注释umask(0000(。

当我出现错误时，这是symfony2日志的最后一行：

[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "JMS'I18nRoutingBundle'EventListener'CookieSettingListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'Security'Http'Firewall'ContextListener::onKernelResponse". [] []
[2015-09-04 11:20:57] security.DEBUG: Write SecurityContext in the session [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Bridge'Monolog'Handler'FirePHPHandler::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Bridge'Monolog'Handler'ChromePhpHandler::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'HttpKernel'EventListener'ResponseListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'HttpKernel'EventListener'EsiListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'Security'Http'RememberMe'ResponseListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Sensio'Bundle'FrameworkExtraBundle'EventListener'HttpCacheListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'HttpKernel'EventListener'ProfilerListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Bundle'WebProfilerBundle'EventListener'WebDebugToolbarListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'HttpKernel'EventListener'SaveSessionListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.response" to listener "Symfony'Component'HttpKernel'EventListener'StreamedResponseListener::onKernelResponse". [] []
[2015-09-04 11:20:57] event.DEBUG: Notified event "kernel.terminate" to listener "Symfony'Bundle'SwiftmailerBundle'EventListener'EmailSenderListener::onTerminate". [] []

apache错误日志：

[Fri Sep 04 11:24:49 2015] [error] [client my.ip.here] Premature end of script headers: app_dev.php

当我使用app.php 时，prod中不存在问题

系统日志中没有关于此的行。我在同一服务器上的其他网站上没有问题。我没有硬盘空间问题。

有人有主意吗？thx

app_dev.php文件：

<?php

use Symfony'Component'HttpFoundation'Request;
use Symfony'Component'Debug'Debug;

// If you don't want to setup permissions the proper way, just uncomment the following PHP line
// read http://symfony.com/doc/current/book/installation.html#configuration-and-setup for more information
umask(0000);
// This check prevents access to debug front controllers that are deployed by accident to production servers.
// Feel free to remove this, extend it, or make something more sophisticated.
if (isset($_SERVER['HTTP_CLIENT_IP'])
    || isset($_SERVER['HTTP_X_FORWARDED_FOR'])
    || !in_array(@$_SERVER['REMOTE_ADDR'], array('127.0.0.1', 'xxx.xxx.xxx.xxx'))
) {
    header('HTTP/1.0 403 Forbidden');
    exit($_SERVER['REMOTE_ADDR'].' : You are not allowed to access this file. Check '.basename(__FILE__).' for more information.');
}
$loader = require_once __DIR__.'/../app/bootstrap.php.cache';
Debug::enable();
require_once __DIR__.'/../app/AppKernel.php';
$kernel = new AppKernel('dev', true);
$kernel->loadClassCache();
$request = Request::createFromGlobals();
$response = $kernel->handle($request);
$response->send();
$kernel->terminate($request, $response);

对于apache配置，它是isp-config配置，我刚刚为这个网站添加了这个：

Apache指令：

DocumentRoot /var/www/clients/client2/web56/web/symfony/web/
FcgidMaxRequestLen 20000000

php.ini：

apc.shm_size = 256M
realpath_cache_size = 4096k
realpath_cache_ttl=7200
session.auto_start = 0
xdebug.remote_autostart=0
xdebug.remote_enable=0
xdebug.profiler_enable=0

在config_dev.yml中，如果我从monlog配置中删除firephp和chromephp，问题就解决了。我认为这不是一个好的解决方案，有人有其他想法吗？