title: Network Adapter Error when connecting to Oracle with SQL Developer on MacOS High Sierra
body: <p>Keep getting the following error:
  &quot;Status : Failure -Test failed: IO Error: The Network Adapter could not establish the connection&quot;
  when trying to connect to the Oracle database on my local machine. I've successfully logged on before, but when I try and rejoin a connection it presents this error.</p>
  <p>I've tried re-installing, connecting as sys or other usernames, but the error keeps returning.</p>