Introduction
ORA-12514 is a common error among database administrators and developers, which indicates a failure in establishing a database connection or a communication problem between the client and the server.
Causes of ORA-12514 Error
The ORA-12514 error occurs due to various reasons, such as:
- The TNS listener is not running or is configured incorrectly
- The database instance is not running or is not available
- The connection string is wrong or incomplete
- The network connection between the client and the server is unstable or lost
Solutions for ORA-12514 Error
The following solutions can help you to resolve the ORA-12514 error:
- Check if the TNS listener is running and configured correctly. You can use the `lsnrctl` command to start or stop the listener and `tnsping` command to test the listener’s connectivity.
- Ensure that the database instance is running and available. You can use the `ps -ef|grep pmon` command to check if the instance is running or not.
- Verify that the connection string is correct and complete. The string should include the following information: the database name, host name, port number, and service name.
- Check the network connection between the client and the server. You can use the `ping` command to test the connection’s stability and ensure that there is no firewall blocking the connection.
If the above solutions don't work, you can try to troubleshoot the issue by checking the listener log file and database alert log file. These files can provide useful information on the cause of the error.
Conclusion
In conclusion, the ORA-12514 error is a common database connection error that can occur due to various reasons. By using the above solutions, you can quickly diagnose and resolve the error, which can save you time and effort.