'A string describing why the last scan failed, or None if it didn\'t.'

@property
def scan_error(self):

    self.acquire_lock()
    try:
        if (self._scan_error_cache is None):
            try:
                self._load_buf_data_once()
            except NotFoundInDatabase:
                pass
        return self._scan_error_cache
    finally:
        self.release_lock()
