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ORA-12502 TNS-12502 TNS:LISTENER RECEIVED NO CONNECT_DATA FROM CLIENT

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.

Below is the sample entry of tnsnames.ora:-

#When using SERVICE_NAME in CONNECT_DATA component
orcl.example.com =
   (DESCRIPTION =
     (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = myserver.example.com)(PORT = 1521))
     )
     (CONNECT_DATA =
       (SERVICE_NAME = orcl)
     )
   )

#When using SID in CONNECT_DATA component 
orcl.example.com =
   (DESCRIPTION =
     (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = myserver.example.com)(PORT = 1521))
     )
     (CONNECT_DATA =
       (SID = orcl)
     )
   )

So for the service name please ensure you have the CONNECT_DATA clause in the tnsnames.ora, if you don’t have one please choose a SERVICE_NAME or SID clause.

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