TNS-12535:  TNS: operation timed out

‘nt secondary err code: 60’ , which indicates that from the Windows OS TCP/IP layer has been raised a timeout , which has been translated under Oracle in these informational messages.

Operating system level:

Check that there is no firewall blocking the traffic on port 1521

The TNS-12535 or ORA-12535 error is commonly a timeout error associated with Firewalls or slow Networks.

Oracle Level:
Check  incorrect “timeout” parameter setting for the following files:

listener.ora -->
INBOUND_CONNECT_TIMEOUT_ =

sqlnet.ora –>
SQLNET.INBOUND_CONNECT_TIMEOUT
sqlnet.expiry_time = 0 (indefinite time)
sqlnet.expiry_time increase the time limit for the connectivity.

Note: TNS-12170/ ORA-12170 at connection time

Least chance is that slow connections to the database

You can used parameter PRE_PAGE_SGA for increased the process startup duration. not recommended to set.

Every process when starts must access page in the SGA. Solution for TNS-12170/ ORA-12170 at connection time