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ORA-12203: TNS: Unable to Connect to Destination tips

Oracle Error Tips by Burleson Consulting


Oracle docs note this about ORA-12203

ORA-12203: TNS:unable to connect to destination

Cause: Invalid address specified or destination is not listening. This error can also occur because of underlying network or network transport problems.

Action: Verify that the net service name you entered was correct. Verify that the ADDRESS portion of the connect descriptor which corresponds to the net service name is correct. Ensure that the destination process (for example the listener) is running at the remote node.

There are a number of reasons to get an TNS-12203.

The ORA-12203 can be the result of an invalid TNS address. In an attempt to eliminate the TNS-12203, verify that the service name is correct and that the name of the host computer defined as part of the TNS address is also valid and correct.

Obviously the other problem, as stated in the Oracle documentation about ORA-12203, the destination may not be not listening. Eliminating the TNS-12203 may involve insuring that the listener is running at the remote node. If the listener service is not running, does not exist and the database has just been newly created on the machine by restoring it from a backup, the listener service will need to be created in order to resolve the ORA-12203.

If you are experiencing ORA-12203 with a failing listener, you may want to first do some troubleshooting.  From this great article, we can see that the first step in resolving TNS-12203 is to check the listener log to figure out why the listener is not starting and why ORA-12203 is being thrown:


For resolving an TNS-12203 error, the database alert log may also be a good resource to make sure the database is actually starting.

Also, it is important to note that if you are experiencing ORA-12203 in newer versions of Oracle, you may be experiencing the brunt of an Oracle bug.  To resolve ORA-12203, you can apply the ADI rollup patch, in order to remedy the 4219255 bug.



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