Fresh Oracle Errors Interview Questions & Answers:

1. ORA-12502: TNS:listener received no CONNECT_DATA from client?

Cause: No CONNECT_DATA was passed to the listener.

Action: Check that the service name resolved from
TNSNAMES.ORA has the CONNECT_DATA component of the connect
descriptor.

2. ORA-12504: TNS:listener was not given the SID in CONNECT_DATA?

Cause: The SID was missing from the CONNECT_DATA.

Action: Check that the connect descriptor corresponding to
the service name in TNSNAMES.ORA has an SID component in the
CONNECT_DATA.

3. ORA-12505: TNS:listener does not currently know of SID given in connect descriptor?

Cause: The listener received a request to establish a
connection to a database or other service. The connect
descriptor received by the listener specified a SID for an
instance (usually a database instance) that either has not
yet dynamically registered with the listener or has not been
statically configured for the listener. This may be a
temporary condition such as after the listener has started,
but before the database instance has registered with the
listener.

4. ORA-12508: TNS:listener could not resolve the COMMAND given?

Cause: d by incompatible Oracle Net or Net8 versions. Do not
include in error manual.

Action: This is not seen in normal use of Oracle Net.

5. ORA-12509: TNS:listener failed to redirect client to service handler?

Cause: The dispatcher terminated unexpectedly

Action: Attempt to connect again and if the same error
occurs, contact the DBA to check the state of the
dispatchers for this SID. If the problem persists, turn on
tracing in the listener to determine the TNS error caused by
the redirect.

6. ORA-12510: TNS:database temporarily lacks resources to handle the request?

Cause: The dispatchers appear to be busy handling other
requests.

Action: Attempt the connection again. If error persists, ask
the DBA to increase the number of dispatchers and/or
dispatchers' limit on number of connections/sessions that
they can accept.

7. ORA-12511: TNS:service handler found but it is not accepting connections?

Cause: The dispatchers notified the listener that they
temporarily do not accept new connections.

Action: Attempt the connection again. If error persists,
contact the DBA to check the state of the dispatchers and/or
ask him to increase the number of dispatchers.

8. ORA-12513: TNS:service handler found but it has registered for a different protocol?

Cause: The dispatchers registered for this service are
connected to the listener by way of a different network
protocol than that of the client.

Action: Contact the DBA to register a dispatcher on your
protocol.

9. ORA-12514: TNS:listener does not currently know of service requested in connect descriptor?

Cause: The listener received a request to establish a
connection to a database or other service. The connect
descriptor received by the listener specified a service name
for a service (usually a database service) that either has
not yet dynamically registered with the listener or has not
been statically configured for the listener. This may be a
temporary condition such as after the listener has started,
but before the database instance has registered with the
listener.

10. ORA-12515: TNS:listener could not find a handler for this presentation?

Cause: None of the listener's known service handlers are
registered as supporting the presentation protocol required
by the connecting client.

Action: Check that the destination service is configured to
accept the presentation protocol.