Oracle Errors Interview Preparation Guide
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Oracle Errors frequently Asked Questions by expert members with experience in Oracle Errors. These interview questions and answers on Oracle Errors will help you strengthen your technical skills, prepare for the interviews and quickly revise the concepts. So get preparation for the Oracle Errors job interview

15 Oracle Errors Questions and Answers:

1 :: ORA-12521: TNS:listener does not currently know of instance 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 in addition to
the service name an instance name 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.
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2 :: ORA-12520: TNS:listener could not find available handler for requested type of server?

Cause: None of the known and available service handlers for
requested type of server (dedicated or shared) are
appropriate for the client connection.

Action: Run "lsnrctl services" to ensure that the
instance(s) have registered with the listener and that the
appropriate handlers are accepting connections.
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3 :: ORA-12519: TNS:no appropriate service handler found?

Cause: The listener could not find any available service
handlers that are appropriate for the client connection.

Action: Run "lsnrctl services" to ensure that the
instance(s) have registered with the listener, and are
accepting connections.
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4 :: ORA-12518: TNS:listener could not hand off client connection?

Cause: The process of handing off a client connection to
another process failed.

Action: Turn on listener tracing and re-execute the
operation. Verify that the listener and database instance
are properly configured for direct handoff. If problem
persists, call Oracle Support.
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5 :: ORA-12516: TNS:listener could not find available handler with matching protocol stack?

Cause: None of the known and available service handlers for
the given SERVICE_NAME support the client's protocol stack:
transport, session, and presentation protocols.

Action: Check to make sure that the service handlers (e.g.
dispatchers) for the given SERVICE_NAME are registered with
the listener, are accepting connections, and that they are
properly configured to support the desired protocols.
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6 :: 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.
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7 :: 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.
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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.
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9 :: 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.
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10 :: 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.
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