To be consistent with Symfony, the exception message should be kept in English and the translation key should be returned by ``getMessageKey`` in the exception (you should provide a subclass changing the message key for your different cases), which would then be translated in the ``security`` domain.

If you don't do it, this system would be incompatible with the Symfony 2.3+ (maybe 2.2+, I don't remember when it was added) i18n system for auth errors