Hi,
Sometimes You can get “TNS-12203: TNS:unable to connect to destination ” error.
Details of error are as follows.
TNS-12203: TNS:unable to connect to destination
Cause: Invalid address specified or destination is not listening.
This error can also occur because of underlying network or network transport problems.
Action: Verify that the net service name you entered was correct.
Verify that the ADDRESS portion of the connect descriptor which corresponds to
the net service name is correct. Ensure that the destination process
(for example the listener) is running at the remote node.
To solve this error, check your the client version if it is compatible with your Database and Listener.
If they are incompatible, then add these two lines to the sqlnet.ora
SQLNET.ALLOWED_LOGON_VERSION_SERVER=8
SQLNET.ALLOWED_LOGON_VERSION_CLIENT=8
Or check the firewall settings and disable the firewall as follows.
service iptables stop chkconfig iptables off service ip6tables stop chkconfig ip6tables off
You can disable firewall in Redhat with below script.
systemctl stop firewalld systemctl disable firewalld
Do you want to learn more details about RMAN, then read the following articles.
https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/