Sometimes you will see the error message related to tns.

Error message will be like this.

ORA-12154: TNS could not resolve service name specified

Solutions

1. Check if your listener is up and running
2. Check if listener is listening to database services.
3. Look for tnsnames.ora file. database entry needs to be available there
4. Syntax error in tnsnames.ora
5. Service name might have an alias, so check for global entries and local entries

Location of tnsnames.ora and listener.ora will be as $ORACLE_HOME/network/admin/

Thanks for visiting this post. Please contact us if you are looking for training.
Subscribe to our channel for unlimited learning. Thank you!!!