title: 'An image does not exist locally with the tag' error in docker PUSH command
body: <p>I am new to docker. I have the following two docker image files that I downloaded from docker hub </p>
  
  <pre><code>(1) Cassandra:3 
  (2) Kong
  </code></pre>
  
  <p>I have Gitlab Repository into which I want to push these two images. I am able to connect to the Gitlab Registry. I am trying to push the Cassandra:3 Image using the following command.</p>
  
  <pre><code>docker push registry-gitlab.mycompany.com/username/myproject/cassandra:3
  </code></pre>
  
  <p>When I execute the above command I get the following error.</p>
  
  <pre><code> The push refers to repository [registry-gitlab.mycompany.com/username/myproject/cassandra]
  An image does not exist locally with the tag: registry-gitlab.mycompany.com/username/myproject/cassandra
  </code></pre>
  
  <p>There is an image called cassandra with tag 3 in the system where I am executing the push command. After going through similar questions in stackoverflow, I assume that this relates to Tag name, but I am not sure what should be the tag name to be assigned to this image or whether updating tags will have any issue.</p>