Giving below error when trying to connect from Oracle client
“ORA-21561 : OID generation failed”
ORA-21561 : OID generation failed
Enter user-name: <username>/<password> @ <tns connect string>
Then the problem is most likely in the client machine hosts file.
Check that there is client machine fully qualified name and short name in the client machine hosts file. If these are missing you’ll get ORA-21561 errors when trying to connect server.
127.0.0.1 localhost.localdomain localhost
Thank You !!