title: sagemaker notebook instance failed to run even a single line of code
body: <p>l am running a notebook instance as usual.</p>
  <p>But suddenly something was wrong. The notebook failed to give out anything. So l use a simple line of code to test it, which returns the following result:
  <a href="https://i.stack.imgur.com/o6h2t.png" rel="nofollow noreferrer">my test result</a></p>
  <p>The notebook even failed to run so simple a code, and the kernel is showing a 'busy' state.(right-up corner)</p>
  <p>Simultaneously I'm running another .py file through the terminal, which works well all along.</p>
  <p>Anyone gets an idea? Thanks for any possible reason told.</p>
  <p>instance <a href="https://i.stack.imgur.com/AW09e.png" rel="nofollow noreferrer">instance</a></p>
  <p>My log console
  <a href="https://i.stack.imgur.com/TxKhy.png" rel="nofollow noreferrer">log console</a></p>