This error is received when the listener received a request to establish a connection to a database or other service but 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…
This error occurs when there was no default service configured for the listener and SERVICE_NAME was missing from the request received by the listener. When a user tries to connect to the listener, it may be servicing several different databases. If user specifies a service name in the connect request then the listener will connect…
This is a quick note to cover ORA-12547: TNS:lost contact error, I would try to include all possible causes of ORA-12547: TNS:lost contact error so that this post itself could assist you in sorting the issue. ORA-12547: TNS:lost contact error could be due to any of the following reasons:- Incorrect permissions on the ORACLE executable.…
Oracle Database Internal Mechanism 