DBT-06103 The port (1,521) is already used

Thanks Tornike Kupatadze for this testing case!

Problem:

During my OCA class, after successful 19c database software installation, we were creating a database using dbca and got the following error:

If the listener had already been configured we would have had an error DBT-06103 The port (5,500) is already used while configuring EM express. But still, the solution is the same.

We have checked and the port was not used:

# netstat -a |grep 1521

Reason:

The hostname is not reachable. The reason in our case was that /etc/hosts did not contain entries about this server.

Solution:

Qualify the hostname into the /etc/hosts:

After adding the above entry, we were able to continue.