ORA-12541: TNS:no listener

I get the ORA-12541 error message when I try to connect through sqldeveloper/Navicat. I’ve started the listener also. I’ve checked the listener.ora and tnsnames.ora files and everything seems okay.

There is a root Cause: Listener for the source repository has not been started.

Action: Start the Listener on the machine where the source repository resides.

From the command-line, type the following command:

lsnrctl start

The problem is gone. Viel Glück 🥠
Nam Le