ORA-12154: TNS:could not resolve the connect identifier specified

ORA-12154 is an Oracle error code that indicates that the Oracle client or application is unable to establish a connection to an Oracle database because it cannot find the database service or network name. This error typically occurs when the connect identifier specified in the connection string is incorrect or cannot be resolved.

To resolve this error, you should first verify that the connect identifier is correct and can be resolved by the network. You can do this by checking the tnsnames.ora file located in the Oracle Home directory of your client. Make sure that the service name specified in the connect string matches the service name defined in the tnsnames.ora file.

You can also try adding an entry for the database service in the tnsnames.ora file if it does not already exist. Once you have verified that the connect identifier is correct, you should try connecting to the database again. If the error persists, you may need to check your network configuration or contact your database administrator for assistance.