Oracle error codes


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

This is an Oracle Database Server Message. This can be generated by the Oracle Database when running any Oracle program.

What is the cause of ORA-12154 from Oracle 11g ?

A connection to a database or other service was requested using a connect identifier, and the connect identifier specified could not be resolved into a connect descriptor using one of the naming methods configured. For example, if the type of connect identifier used was a net service name then the net service name could not be found in a naming method repository, or the repository could not be located or reached.

How to fix ORA-12154 from Oracle 11g ?

This is in general the very first error message you get when you try to establish a connection to your oracle database. Often, it's a typographical error in your connexion string or in your tnsnames.ora file.

If you are using local naming (TNSNAMES.ORA file):

- Make sure that "TNSNAMES" is listed as one of the values of the NAMES.DIRECTORY_PATH parameter in the Oracle Net profile (SQLNET.ORA)

- Verify that a TNSNAMES.ORA file exists and is in the proper directory and is accessible (general tnsnames.ora location is: $ORACLE_HOME/network/admin/tnsnames.ora).

- Check that the net service name used as the connect identifier exists in the TNSNAMES.ORA file.

- Make sure there are no syntax errors anywhere in the TNSNAMES.ORA file. Look for unmatched parentheses or stray characters. Errors in a TNSNAMES.ORA file may make it unusable.

If you are using directory naming:

- Verify that "LDAP" is listed as one of the values of the NAMES.DIRETORY_PATH parameter in the Oracle Net profile (SQLNET.ORA).

- Verify that the LDAP directory server is up and that it is accessible.

- Verify that the net service name or database name used as the connect identifier is configured in the directory.

- Verify that the default context being used is correct by specifying a fully qualified net service name or a full LDAP DN as the connect identifier

If you are using easy connect naming:

- Verify that "EZCONNECT" is listed as one of the values of the NAMES.DIRETORY_PATH parameter in the Oracle Net profile (SQLNET.ORA).

- Make sure the host, port and service name specified are correct.

- Try enclosing the connect identifier in quote marks. See the Oracle Net Services Administrators Guide or the Oracle operating system specific guide for more information on naming.

How to solve ORA-12154 ?

How to deepen your knowledge about Oracle?

You can train yourself with many books and get an advantage over your competitors by developing a set of skills highly sought throughout the world. Niels Bohr saw an expert as "a person who has found out by his own painful experience all the mistakes that one can make in a very narrow field". So why not you? Be an expert!
To that aim, the first reference book I would suggest is "Oracle Database 11g The Complete Reference (Oracle Press)Oracle Database 11g The Complete Reference" by Kevin Loney. This internationally recognized Oracle expert was named Consultant of the Year by ORACLE Magazine in 2002. Also be aware that the 12c Oracle version is available on here : Oracle Database 12c The Complete Reference (Oracle Press).
In addition to that, let me suggest "OCP Oracle Certified Professional on Oracle 12c Certification Kit" as further reading in order to improve your skills and pass your first level certification.

Your comments (0 comment)

Whether the above information has been helpful to you or not, we would appreciate reading your comments below. Also feel free to ask questions.

Leave a comment

Bibliography

Oracle Database 11g The Complete Reference (Oracle Press)Oracle Database 11g The Complete Reference

Oracle Database 11g The Complete ReferenceOracle Database 11g The Complete Reference

The Definitive Guide to Oracle Database 11g.
Get full details on the powerful features of Oracle Database 11g from this thoroughly updated Oracle Press guide. Oracle Database 11g: The Complete Reference explains how to use all the new features and tools, execute powerful SQL queries, construct PL/SQL and SQL*Plus statements, and work with large objects and object-relational databases. Learn how to implement the latest security measures, tune database performance, and deploy grid computing techniques. An invaluable cross-referenced appendix containing Oracle commands, keywords, features, and functions is also included.

Author:

OCP Oracle Certified Professional on Oracle 12c Certification Kit

Meet your certification guide on the journey to Oracle DBA
The Oracle DBA Certification track now consists of three levels – Associate (OCA), Professional (OCP), and Master (OCM). This valuable kit helps you attain success at each level, providing clarification of the complex material along with plenty of practice that covers all exam objectives.
OCP Oracle Certified Professional on Oracle 12c Certification Kit is the ideal tool for preparing for the OCA and OCP exams. With two comprehensive study guides in one package, this kit serves as a helpful companion throughout your journey to Oracle DBA certification. The OCA study guide is designed for those with some Oracle experience and a background in operational management and maintenance, covering one hundred percent of the material on exams 1Z0-061 and 1Z0-062. Once you're OCA certified, the OCP guide prepares you for exam 1Z0-063 by drawing on your experience with backup, recovery, and cloud computing to master database architecture, RMAN, multitenant architecture, and more. Along the way, you'll have access to robust study tools including review questions, bonus practice exam questions, electronic flashcards, and an appendix of additional lab exercises that give you hands-on experience in preparation for exam day.

Authors: , , , ,

Contacting Oracle support services ?

Some messages recommend contacting Oracle Support Services to report a problem. Please go here for more information : Oracle Support.

Linked Oracle error codes

  • ORA-12150 TNS:unable to send data
  • ORA-12151 TNS:received bad packet type from network layer
  • ORA-12152 TNS:unable to send break message
  • ORA-12153 TNS:not connected
  • ORA-12155 TNS:received bad datatype in NSWMARKER packet
  • ORA-12156 TNS:tried to reset line from incorrect state
  • ORA-12157 TNS:internal network communication error
  • ORA-12158 TNS:could not initialize parameter subsystem
  • ORA-12159 TNS:trace file not writeable
  • ORA-12160 TNS:internal error: Bad error number
  • ORA-12161 TNS:internal error: partial data received
  • ORA-12162 TNS:net service name is incorrectly specified