eZ Platform has a incompatibility with Symfony 2.8, as it changes the value of some of it's constants.

Specifically:

• The DefaultRouter tests with $referenceType == self::ABSOLUTE_URL. This should be $referenceType === self::ABSOLUTE_URL as the Symfony CMF ChainRouter will pass false to mean 'not absolute'.
• This is then interpreted incorrectly because of the type coercion as self::ABSOLUTE_URL = 0 and you get a false result.
• You can see\symfony-cmf\routing\ChainRouter.php line 231:
  return $router->generate($name, $parameters, $absolute);