Doctrine error: "Failed opening required '/tmp/__CG__Source.php' "

I am trying to migrate my PHP application to an Ubuntu server, but without succes. Any help would be appreciated.

First I installed Doctrine successfully into /jorrit/myapp, following the first part of Doctrine's Getting Started manual (till "Generating the Database Schema"). Secondly I placed my PHP scripts (which use Doctrine) in folder /jorrit/myapp.

When I try to run my PHP script in the CLI, I get this error messages:

PHP Warning: require(/tmp/__CG__Source.php): failed to open stream: No such file or directory in /jorrit/myapp/vendor/doctrine/common/lib/Doctrine/Common/Proxy/AbstractProxyFactory.php on line 200

PHP Fatal error: require(): Failed opening required '/tmp/__CG__Source.php' (include_path='.:/usr/share/php:/usr/share/pear') in /jorrit/myapp/vendor/doctrine/common/lib/Doctrine/Common/Proxy/AbstractProxyFactory.php on line 200

Bootstrap.php looks like this:

<?php
// bootstrap.php
use Doctrine\ORM\Tools\Setup;
use Doctrine\ORM\EntityManager;

require_once "vendor/autoload.php";

// Create a simple "default" Doctrine ORM configuration for Annotations
$isDevMode = false;
$config = Setup::createAnnotationMetadataConfiguration(array(__DIR__."/src"), $isDevMode);

// the connection configuration
$dbParams = array(
        'driver'   => 'pdo_mysql',
        'host'     => 'xx',
        'user'     => 'xx',
        'password' => 'xx',
        'dbname'   => 'xx',
        'profiler' => 'false'
);


// obtaining the entity manager
$entityManager = EntityManager::create($dbParams, $config);

?>

The first lines of my PHP script:

<?php

require_once "bootstrap.php";
require_once 'classes.php';

$connection = $entityManager->getConnection();

The application works fine in my development environment (Windows). The /tmp folder exists and is accessible. The database is migrated succesfully and exists. I did not change anything in the vendor folder.

Any ideas? Thanks in advance for your help.