SP2-0157: Unable to Connect to Oracle Database - Troubleshooting Guide

SP2-0157 is an error message indicating that SQL*Plus was unable to connect to the Oracle database after three attempts. This typically happens when the connection parameters provided are incorrect or there is an issue with the database server.

To resolve this issue, you can try the following steps:

1. Verify the connection parameters: Double-check the username, password, hostname, and port number provided for the database connection. Ensure that they are correct.

2. Check the database server status: Ensure that the Oracle database server is running and accessible. You can try to ping the server to check its availability.

3. Check the listener status: If the database server is up and running, check the status of the Oracle listener. The listener is responsible for establishing connections to the database. To check the listener status, you can use the 'lsnrctl status' command in the command prompt or terminal.

4. Check the firewall settings: If you are connecting to a remote database, make sure that there are no firewall restrictions blocking the connection.

5. Restart the Oracle database: If none of the above steps resolve the issue, you can try restarting the Oracle database server. This can often resolve any temporary issues that might be causing the connection problem.

If the issue persists, it is recommended to contact your database administrator or Oracle support for further assistance. They will be able to provide more specific guidance based on your environment and configuration.