Understanding SQL*Net Go to Product Documentation Library
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Common Error Messages

Ideally, your installation, configuration, and use of SQL*Net will go smoothly, and you will have no problems. However, inevitably errors will occur. All the error messages you may receive when using Oracle networking products are described in the Oracle Network Products Troubleshooting Guide. However, for your convenience, this appendix describes seven of the most common error messages in detail. They are:

For information on other error messages, and to learn more about error logging and the trace facility, see the Oracle Network Products Troubleshooting Guide.

Common Sources of Error: Configuration Files

The most common cause of problems in making a SQL*Net connection is in the structure or location of the configuration files.

Syntax Errors

The syntax of the files must be followed precisely. If you create the files using Network Manager, syntax errors should not occur. However, if you create or edit them by hand, check them carefully to see that all the appropriate parentheses are in place, that the lines are indented to show their logical structure, and that there are no typographical errors. See Appendix B, "Syntax Rules for Configuration Files," for details on the syntax of these files. Be sure that all service names are mapped to connect descriptors in the TNSNAMES. ORA file.

Location Errors

The TNSNAMES.ORA file must be distributed so that it is available to all nodes that make connections using SQL*Net version 2 (unless Oracle Names is being used on the network).

A unique LISTENER.ORA file must be distributed to each node that includes one or more databases.

In a network that includes one or more Interchanges, a unique TNSNAV.ORA file must be available to all the clients which have similar navigation requirements.

Every node with an Interchange must have an INTCHG.ORA, a TNSNET.ORA, and a TNSNAV.ORA file.

See the Oracle operating system specific manual for your platform for the exact locations of these files.

Common Sources of Error: Inactive Components

Before you can use a SQL*Net network, a transport layer protocol and an Oracle Protocol Adapter must be installed.

Be sure that you have started the listener for any server you intend to contact. For instructions on starting the listener using the Listener Control Utility, see Chapter 5, ``Using SQL*Net".

If you are making a connection across protocols using one or more Interchanges, the Interchanges must be started. For instructions on starting an Interchange using the Interchange Control Utility, see Chapter 6 in the Oracle MultiProtocol Interchange Administrator's Guide.

Common Error Messages

The following error messages are among those most often encountered by SQL*Net users. For a complete list of SQL*Net error messages, their causes and the action to take if you get them, see Chapter 3 in the Oracle Network Products Troubleshooting Guide.

ORA-12154 TNS:could not resolve service name

This error points to a problem related to Oracle Names or the TNSNAMES.ORA file. The service name specified cannot be located through either a Names Server or the TNSNAMES.ORA file. If you get this error, do the following:

			namesctl status names_server_name

			namesctl query service_name *

ORA-12198 TNS:could not find path to destination

This error indicates a failure of navigation across protocols through one or more Interchanges. If you get this error, do the following:

If the error persists, it may be useful to check for errors in the Interchange log files. A different error in the connection process can sometimes be reported as a 12198.

ORA-12203 TNS:unable to connect to destination

This message indicates that the client is not able to find the desired database. If you get this message, do the following:

This error often is reported because the destination node is not available or because of unrelated network problems.

ORA-12500 TNS:listener failed to start a dedicated server process

This message indicates that the listener was unable to start a process connecting the user to the database server. The most likely cause is that the SID_LIST section of the LISTENER.ORA file or the system identifier (SID) in the CONNECT DATA section of the TNSNAMES.ORA file is incorrect. Check each of these files.

Another possible cause of this message is that the user does not have adequate privileges to access the database. Ask your database administrator to provide you access privileges if you do not have them. Also ask your system administrator to check the ownership and permissions of the database server process image.

ORA-12533 TNS:illegal ADDRESS parameters

This message occurs if the protocol specific parameters in the ADDRESS section of the designated connect descriptor in TNSNAMES.ORA are incorrect. The protocol specific keywords, and their acceptable values, can be found in the Oracle operating specific documentation for your platform.

If you use Network Manager to create the TNSNAMES.ORA file, the correct protocol specific keywords are included automatically.

ORA-12545 TNS:name lookup failure

This message occurs when the listener on the remote node cannot be contacted. The ADDRESS in the TNSNAMES.ORA file or the LISTENER.ORA file may be incorrect. This message may also appear if the listener on the remote node has not been started. Check its status with the STATUS command of the Listener Control Utility, and start it with the START command if necessary.

ORA-12560 TNS:protocol adapter error

This message indicates that there is a problem at the protocol adapter level. That is, SQL*Net and the Interchange are functioning correctly, but there is something wrong with the protocol adapter that underlies them. The Oracle operating system-specific documentation for your platform contains more information about the protocol adapters.

In order to get more information about the specific problem, turn on tracing and re-execute the operation. (Because tracing and trace files use a lot of disk space, be sure to turn off tracing as soon as the trace is complete.) The trace file includes information about the specific protocol adapter problem. If you have trouble interpreting the trace file, contact Worldwide Customer Support for assistance, following the procedures described in Chapter 1 of the Oracle Network Products Troubleshooting Guide.

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