Cannot create connection in Oracle SQL Developer

Question

I am a new user in Oracle. In Oracle SQL Developer, whenever I want to create a new connection and fill the "New Database Connection" form, it gives me this error: -

ORA-12560: TNS:protocol adapter error

Please Help.

Answer 1

To add more to my comment on the question...

Ensure your database is open (has been started up).

1. Start all oracle services for your database
2. Start the databases listener (lsnrctl start)
3. Startup your database instance (startup open <database_name>)

Also, ensure the database you are trying to connect to has an entry in the tnsnames.ora file your SQL Developer is using (depending upon your setup you may have a tnsnames.ora for both your oracle client and database software if they are on the same physical hardware like your PC or laptop).

Answer 2

I've faced that kinda problem also and I've tried stop all of oracle services and start it again. But unsuccessful. Eventually, I've needed to install Oracle again which can solve this problem.