我看了官方关于这个问题的回答，是说要安装最新版本就可以解决。

好吧，我去查了一下VisualDL的LogWriter类的源码，确实没有mode属性。。。建议改成这样来用：

writer = LogWriter(logdir="./log/")
writer.add_scalar(tag="train/acc", step=1, value=0.5678)
# multi-level tags is allowed.
writer.add_scalar(tag="train/second/acc/acc_a", step=1, value=0.1234)
# Use writer.flush() or writer.close() to make sure all data in memory will written to disk.
writer.close()

查看源码了，确实，用add_scalar替代吧。

 def add_scalar(self, tag, value, step, walltime=None):
        """Add a scalar to vdl record file.

        Args:
            tag (string): Data identifier
            value (float): Value of scalar
            step (int): Step of scalar
            walltime (int): Wall time of scalar

        Example:
            for index in range(1, 101):
                writer.add_scalar(tag="train/loss", value=index*0.2, step=index)
                writer.add_scalar(tag="train/lr", value=index*0.5, step=index)
        """
        if '%' in tag:
            raise RuntimeError("% can't appear in tag!")
        walltime = round(time.time() * 1000) if walltime is None else walltime
        self._get_file_writer().add_record(
            scalar(tag=tag, value=value, step=step, walltime=walltime))