title: SQL Developer Lost all Connections
body: <p>I am trying to connect to oracle database using SQL Developer. For the last 2 years I never had any issues but all of a sudden, all connections were lost. I tried to add new a one, and the connection is testing successfully. But when I clicked on the Connect button nothing happens. </p>
  
  <p>I tried updating the java version to latest one, but the problem still persists.</p>
  
  <p>What could be the issue? Is it related to Firewall?</p>