Oracle Solution for Error ora-12520

ORA-12520: TNS:listener could not find available handler for requested type of server

What triggered the Error:

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

What should we do to fix it:

Run "lsnrctl services" to ensure that the instance(s) have registered with the listener and that the appropriate handlers are accepting connections.