def process_500(self, request, exception):
        '''Internal server error.'''
        id_ = str(uuid.uuid4())[:6].upper()
        msg = 'Internal server error: 500. Unique error identifier is {}'
        msg = msg.format(id_)
        log.error('HTTP 500 [Message - {}]: {}'.format(id_, msg))
        log.error('HTTP 500 [Arguments - {}]: {}'.format(id_, request.args))
        log.exception('HTTP 500 [Traceback - {}]:'.format(id_))
        return msg
Internal server error.