Error with SystemExit：exception :no description when the training is complete in tf.app.run

[corin-lyz]

The problem is following:
when the training or test is complete, and all the training data is displayed and the model is saved.However,
The Error with SystemExit was appear in tf.app.run(),The error message likes this: SystemExit：exception :no description.
I desire your nice ideas,Thenk you!