title: How to downgrade Keras in colab ? "NotFoundError: No algorithm worked!"
body: <p>I was getting the error <strong>&quot;NotFoundError: No algorithm worked!&quot;</strong> on an architecture that was developed based on the older versions of tensorflow (pre-2.0.0 versions), and that is run on Colab.
  Now, Google Colab has an updated version of Tensorflow (post-2.0.0 versions) and Keras.</p>
  <p>Following the question that was asked here I downgraded Tensorflow to 1.15.0 : <a href="https://stackoverflow.com/questions/51888118/how-to-downgrade-tensorflow-version-in-colab">How to downgrade tensorflow version in colab?</a>
  I used this command to downgrade Tensorflow :</p>
  <pre><code>!pip install tensorflow==1.15.0 
  import tensorflow as tf
  </code></pre>
  <p>Still, I have a problem importing Keras.</p>