tf.Summary()报错，是咋回事？

faster R-cnn中自定义tensorboard部分的代码报错，代码如下

def write_log(callback, names, logs, batch_no):
    for name, value in zip(names, logs):
        summary = tf.Summary()
        summary_value = summary.value.add()
        summary_value.simple_value = value
        summary_value.tag = name
        callback.writer.add_summary(summary, batch_no)
        callback.writer.flush()

报错如下：

AttributeError: module 'tensorflow' has no attribute 'Summary'

之前运行都ok，突然报这么一个错，没找到解决办法，求路过大神帮忙看看