ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:777)5-classifier_example.py

In the 5-classifier_example.py, when I run (X_train, y_train), (X_test, y_test) = mnist.load_data() in the Pycharm

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error: ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:777) but when I run in the ipython, no error...

why?