During the operation of an Oracle database, errors can occur. One of the most common is ORA-12154: TNS: could not resolve the connect identifier specified. Why does it happen, and how can it be dealt with? In the article, DB Serv experts will provide detailed information about why the error appears and how it can be resolved independently.
What Is ORA-12154: TNS: Could Not Resolve The Connect Identifier Specified?
ORA-12154: TNS: could not resolve the connect identifier specified is a message that database administrators may encounter when facing issues with connecting to one of your corporate Oracle services.
Please note that this error might be displayed in some versions as ORA-12154: TNS: could not resolve service name. In simpler terms, by sending the ORA-12154 message, the database indicates that an attempt was made to connect to a service whose name is not registered in the system.
What Causes ORA-12154 Error To Occur?
Most commonly, the ORA-12154: TNS: could not resolve the connect identifier specified error can be caused by the following factors:
➡️ Absence of the tnsnames.ora file.
➡️ Incorrectly specified domain during the search.
➡️ Lack of local naming method.Mismatched connection identifier.
➡️ Error in requested database name aliases.
How to Resolve the ORA-12154 Error in Oracle?
First and foremost, it's important to correctly identify the root cause of the issue. This will explain why your admin cannot connect the database to your services. The error message is typically displayed in the Oracle client app, not on the network server.
The ORA-12154: TNS: could not resolve the connect identifier specified error can be resolved in several ways, depending on the primary reason for its occurrence.
Resolving ORA-12154 Error Codes
Traditionally in the Oracle database, client code is used, which provides three options for locating connection data:
➡️ File named tnsnames.ora: Connecting to the database using a connection identifier that hasn't been converted into a connection descriptor. In the case of this issue, it's necessary to check for the presence of the network service name, acting as a connection identifier, in the tnsnames.ora file, and ensure its correct location in the directory.
➡️ LDAP: Connecting to the database through the use of a directory name. If the error arises in this case, it's important to verify whether the LDAP directory server is running. Next, check whether the database name or network service is configured in it to which the connection is being made. You can also provide the full service name or Distinguished Name LDAP to ensure proper use of the default context.
➡️ Service Name: ORA-12154 may occur when connecting via the Oracle EZCONNECT connection naming method. The error can be resolved by double-checking the accuracy of the specified port, host, and network service name. Sometimes, the issue is resolved by enclosing the connection identifier in quotation marks.
Windows
In the Windows operating system, the network file is usually found in the following folders:
⚫️ ORANTNET80ADMIN
⚫️ ORACLEORA81NETWORKADMIN
⚫️ ORAWIN95NETWORKADMIN
⚫️ ORAWINNETWORKADMIN
UNIX/Linux
In UNIX and Linux operating systems, the files are placed in the following folders:
⚫️ $ORACLE_HOME/network/admin/
⚫️ /etc/
⚫️ /var/opt/oracle/
Final Advice
If you've verified the correctness of file locations and their names, and the ORA-12154: TNS: could not resolve the connect identifier specified error persists, there might be an issue with the connection state. Server malfunctions, network problems, power interruptions – all of these can disrupt the standard connection process.
To quickly resolve the ORA-12154 error and resume operations, seek assistance from specialized experts in Oracle database administration. DB Serv experts will promptly analyze any issues and provide optimal solutions.