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Description

The ORA-29271 error in Oracle Database indicates that a network operation failed because a network connection was not established before the attempt. This typically occurs when using packages like `UTL_HTTP` or `UTL_SMTP` without a proper network setup.

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Error Message

ORA-29271: not connected

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Known Causes

4 known causes

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Database Network Configuration

The database server might not be configured correctly for network communication, preventing outbound connections. 💻

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Firewall Restrictions

A firewall is blocking the connection to the remote server, preventing the database from establishing a network link. 🔒

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Incorrect Host/Port

The host or port specified in the network operation is incorrect or unreachable. ⚠

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Network Connectivity Issues

General network issues are preventing the database server from reaching the intended destination. 🌐

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Solutions

4 solutions available

1. Verify SQL*Net Connectivity easy

Ensure the Oracle client can reach the database listener.

1

From the client machine where you are encountering the ORA-29271 error, open a command prompt or terminal.

2

Use the `tnsping` utility to test the connection to your Oracle Net Service Name (TNS Alias). Replace `your_tns_alias` with the actual alias defined in your `tnsnames.ora` file.

tnsping your_tns_alias

3

If `tnsping` fails with an error like 'TNS-03505: Failed to resolve name' or 'TNS-12541: TNS:no listener', it indicates a problem with your TNS configuration or the listener itself. Verify that `tnsnames.ora` is correctly configured and accessible, and that the listener is running on the database server.

4

If `tnsping` succeeds, it means basic network connectivity to the listener is established. The issue might be with how your application or tool is attempting to connect.

2. Check Application Connection String/Configuration medium

Review and correct the database connection details used by your application.

1

Locate the configuration file or code section responsible for establishing the database connection in your application. This could be a connection string in a configuration file (e.g., `web.config`, `application.properties`, `.env`), or code within your application logic.

2

Carefully examine the connection parameters: Hostname/IP address, Port, Service Name/SID, Username, and Password.

3

Ensure these parameters precisely match the details of your Oracle database and listener. Common mistakes include typos in the hostname, incorrect port number (default is 1521), or an invalid Service Name/SID.

4

If you are using a TNS Alias, confirm that it is correctly spelled and that the corresponding entry in `tnsnames.ora` is accurate.

5

Rebuild or restart your application after making any necessary corrections to the connection configuration.

3. Verify Listener Status and Configuration medium

Confirm that the Oracle listener is running and configured to accept connections.

1

Log in to the Oracle database server as a user with appropriate privileges (e.g., `oracle` OS user).

2

Navigate to the Oracle Home directory.

3

Start the Listener Control utility (`lsnrctl`).

lsnrctl status

4

Examine the output of `lsnrctl status`. Look for the 'Listener' status, which should be 'ready'. Also, check the 'Services Summary' to ensure your database service is registered with the listener.

5

If the listener is not running, start it using `lsnrctl start`. If the database service is not registered, you may need to restart the database or ensure its PFILE/SPFILE is configured correctly to broadcast its service to the listener.

lsnrctl start

6

Check the `listener.ora` file (typically located in `$ORACLE_HOME/network/admin/`) for correct configuration, ensuring it's listening on the expected IP address and port.

4. Restart Application or Client Tool easy

A simple restart can often resolve transient connection issues.

1

If you are using a specific client tool (e.g., SQL Developer, Toad, DBeaver), close and reopen the application.

2

If you are running a script or application that connects to the database, stop and restart the process.

3

This is a quick troubleshooting step that can resolve temporary network glitches or resource contention that might be preventing a valid connection.

Oracle Error ORA-29271: Not Connected