title: Jupyter lab : Server Connection Error: Failed to fetch
body: <p>I have created a Google Dataproc cluster with the optional components Anaconda and Jupyter. When I try to open the Jupyter Lab or Jupyter UI from cluster web interface, some times I am getting the following errors that pop-up in the UI which do not allow me to create or use any notebooks.</p>
  
  <ol>
  <li>Server Connection Error: Failed to fetch</li>
  <li>Server Connection Error: 500. That’s an error. That’s all we know</li>
  </ol>
  
  <p>I am using Dataproc image version 1.3-debian9 with python2.7 which is is created using the following gcloud cmd:</p>
  
  <pre class="lang-sh prettyprint-override"><code>REGION=us-central1
  CLUSTER=spark-jupyter-1-3
  
  gcloud beta dataproc clusters create ${CLUSTER} \
   --region=${REGION} \
   --image-version=1.3 \
   --optional-components=ANACONDA,JUPYTER \
   --enable-component-gateway 
  </code></pre>
  
  <p>Any advise how to resolve this issue? </p>