Hi,
Similar issue i had encounter recently. I had followed the below steps to resolve the problem, looks like tsn error is because of many reasons. you try this and let us see.
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Instead of updating the tnsnames.ora manually, I suggest to create a connection string through Net Manager.
Steps:
1. Open Net Manager.
2. go to Local > Service Naming.
3. After selecting Service Naming, click on Edit menu > Create
4. Give a Net Service Name (any user defined name)
5. Select TCP/IP (Internet Protocol)
6. give the Host Name (IP Address or Host machine name)
7. Service Name : (it should be the global_name of the database)
select * from global_name
8. After completing it, go to File and save Network configuration.
9. Select the connection string created and clikck on command menu > test service.
10. Give the valid user name and password for connecting.
While connecting DB thru SQLPLUS, give the username/password@connectionstring
(conn string created in step 4)
Regards,
Narendran
b_karthii@yahoo.com