🧩 ORA-12514: TNS Listener Does Not Currently Know of Service Requested in Connect Descriptor

 🧩 When connecting to an Oracle database, you may encounter the following error:

ORA-12514: TNS:listener does not currently know of service requested in connect descriptor

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🔎 Cause

This error occurs when the listener is running but it does not recognize the service name specified in your connection string.

Common reasons include:

The database is not registered with the listener.

The service name in the tnsnames.ora file or connection string is misspelled.

The database instance is not open.

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🛠️ Solution

1. Verify Database Services Registered with Listener

Run the command on the database server:

lsnrctl status

Check if your service name appears under Services Summary.

2. Manually Register Database with Listener

Log in as SYSDBA and execute:

ALTER SYSTEM REGISTER;

3. Check SERVICE_NAMES Parameter

Ensure the service name matches what’s in your tnsnames.ora.

SHOW PARAMETER service_names;

If incorrect, set it properly:

ALTER SYSTEM SET service_names='ORCL' SCOPE=BOTH;

4. Correct Your Connection String

If you’re using SQL*Plus or any client tool, ensure the service name matches exactly. Example:

sqlplus user/password@//hostname:1521/ORCL

5. Restart the Listener (if required)

lsnrctl stop

lsnrctl start

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✅ Best Practices

Always double-check service names and listener configurations after creating or cloning a database.

Automate database registration by setting LOCAL_LISTENER properly.

Keep tnsnames.ora entries consistent across client machines.

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⚡ With these steps, the ORA-12514 error can usually be resolved quickly, ensuring a smooth database connection.

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