ORA-12154 is an error generated by the oracle network layer. This TNS
message is thrown during the logon process to a database. This error
indicates that the communication software in Oracle ( SQL *Net or Net8
or equivalent ) did not recognize the host/service name specified in the
connection parameters. This error almost always indicates a
misconfiguration of the oracle tns entriesORA-12154
: TNS : could not resolve service name
error is thrown during the logon process to a database. This error
indicates that the communication software (TNS) in Oracle ( SQL *Net or
Net8 ) did not recognize the host/service name specified in the
For a database name to be recognized, it
must be resolved by Oracle Client. To resolve a name, Oracle client uses
either a TNSNames.ora, A Directory Server or an Oracle Names Server.
This error most likely indicates that the resolution is not working and
that there is an error in the TNSNAMES.ORA or SQLNET.ORA. For database
connectivity to work your database name has to be entered into the
TNSNAMES.ORA at a minimum to make this work. In case you are using a
directory or names server, we recommend that you check your sqlnet.ora
To fix the ORA 12154 error:
Check that the instance
or database name is being typed in correctly. It is sometimes also
referred to as the connect string of the database
Check the tns
names.ora file to validate that the instance name has been entered
correctly. If you are in Unix, validate that there are no control
characters at the end of the instance or database name and that all
paranthesis around the tns entry are properly terminated
everything looks good in tnsnames.ora, validate that the domain name
entry in sqlnet.ora is not conflicting with the full database name
If you are unable to find a solution, best practice
is to delete and recreate the TNS entry to eliminate any character or
control character issues.
If the entry you are looking for in
your tnsnames.ora is missing, use the following procedure to add a new
entry using the SQL*Net Easy configuration utility.
Start>Programs>Oracle >SQL Net Easy Configuration.
Select the option to Add a new instance alias.
Enter the parameters are required in the forms. If you do not have this information, contact your dba.
Confirm the new entry.
Repeat for as many aliases as needed.
ORA-12154 Tips :
Most tnsnames issues arise out of multiple oracle homes, incorrect entries made somewhere in the file etc.
1. Try searching the drive to identify how many tnsnames.ora files you have
Try renaming the tnsnames.ora file in the oracle home where you are
facing the issue and add just the entry you are having an issue with. If
it works, you know that the issue is somewhere else in the file.
3. Use a centralized naming service to avoid most issues with client connectivity and the generation of ORA-12154 errors.ORA 12154