I had this issue and the fix was to make sure in tnsnames.ora the SERVICE_NAME is a valid service name in your database. To find out valid service names, you can use the following query in oracle:
select value from v$parameter where name='service_names'
Once I updated tnsnames.ora to:
TEST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = *<validhost>*)(PORT = *<validport>*))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = *<servicenamefromDB>*)
)
)
then I ran:
sqlplus user@TEST
Success! The listener is basically telling you that whatever service_name you are using isn't a valid service according to the DB