The ORA-12560: TNS:protocol adapter error is a common error encountered in Oracle databases, particularly during database startup or when attempting to connect to a database. This error indicates an issue with the network protocol stack that Oracle uses to communicate with the database. Resolving this error is crucial for ensuring smooth database operations.
ORA-12560: TNS:protocol adapter error
The ORA-12560 error can occur due to several reasons, including:
To resolve ORA-12560, follow these troubleshooting steps:
Ensure that the necessary Oracle services are running. On Windows, check the services in the Services console:
# Open Services console and check for Oracle services services.msc
On Linux, check the status of the Oracle services:
# Check Oracle services on Linux $ ps -ef | grep pmon
Verify that the ORACLE_HOME and ORACLE_SID environment variables are set correctly. On Windows, you can set these variables in the System Properties:
# Set environment variables on Windows set ORACLE_HOME=C:\oracle\product\12.2.0\dbhome_1 set ORACLE_SID=ORCL
On Linux, set these variables in the terminal:
# Set environment variables on Linux $ export ORACLE_HOME=/u01/app/oracle/product/12.2.0/dbhome_1 $ export ORACLE_SID=ORCL
Ensure that the network configuration is correct and that there are no firewall issues blocking the connection. Verify the listener.ora and tnsnames.ora files:
# Check listener.ora and tnsnames.ora for correct configuration $ cat $ORACLE_HOME/network/admin/listener.ora $ cat $ORACLE_HOME/network/admin/tnsnames.ora
Also, verify that the Oracle Listener is running:
# Start the Oracle Listener $ lsnrctl start
Ensure that the user has the necessary permissions to access the Oracle database. On Windows, check the user's group membership. On Linux, verify the user's permissions:
# Check user permissions on Linux $ id oracle
If the error persists, it might be due to issues during the installation of Oracle software. Reinstalling Oracle might resolve the issue.
# Uninstall and reinstall Oracle software
If you receive the ORA-12560 error, first check if the Oracle services are running. On Windows, you can start the services using the command prompt:
# Start Oracle services on Windows net start OracleServiceORCL
On Linux, use the following command:
# Start Oracle services on Linux $ sqlplus / as sysdba SQL> STARTUP
Ensure that the ORACLE_HOME and ORACLE_SID environment variables are correctly set. On Windows, use the command prompt:
On Linux, use the terminal:
Check the listener.ora and tnsnames.ora files to ensure they are correctly configured. Sample entries are:
# listener.ora LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = your_host)(PORT = 1521)) ) ) # tnsnames.ora ORCL = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = your_host)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = ORCL) ) )
If the Oracle Listener is not running, you can start it using the following command:
# Start Oracle Listener $ lsnrctl start
The ORA-12560: TNS:protocol adapter error can be a frustrating issue to encounter, but it is typically resolved by ensuring that the Oracle services are running, the environment variables are set correctly, the network configuration is correct, and the user has the necessary permissions. By following the steps outlined in this guide, you should be able to effectively troubleshoot and resolve this error, ensuring smooth database operations.