title: AWS: None of the Instances are sending data
body: <p>I'm trying to set up an Elastic Beanstalk application with Amazon Web Services however I'm receiving a load of errors with the message <code>None of the instances are sending data</code>. I've tried deleting the Elastic Beanstalk Application and the EC2 instance several times with the sample application and trying again but I get the same error.</p>
  
  <p>I also tried uploading a flask application with AWS Elastic Beanstalk command line tools but then I received the error below:</p>
  
  <pre><code>Environment health has transitioned from Pending to Severe. 100.0 % of the requests to the ELB are failing with HTTP 5xx. Insufficient request rate (0.5 requests/min) to determine application health (7 minutes ago). ELB health is failing or not available for all instances. None of the instances are sending data
  </code></pre>
  
  <p>Why do I get this error and how do I fix it? Thanks.</p>