Oracle Entity Framework Core OracleException.Number: 12592

We are trying to use Oracle Entityframework Core nugget provided by Oracle as explained in below url with .net core 2.1

https://www.youtube.com/watch?v=RDZXJYLUC7I

We followed exactly same steps as above. But when we try to run update-database command, we are getting below error.

I confirm all nuggets were installed successfully.
Also I can see all required dlls are present but still not sure why I am getting below error while update-database command.

I have doubled checked the connection string is OK and same connection string is working fine with EF 6.

We are using oracle 12c.

Please advice what am I missing here ?

PM> update-database

2020-03-26 15:40:45.308871 ThreadID:1 (ERROR) >OracleDatabaseCreator.Exists() : OracleException.Number: 12592
2020-03-26 15:40:45.320461 ThreadID:1 (ERROR) >OracleDatabaseCreator.Exists() : Oracle.ManagedDataAccess.Client.OracleException (0x80004005): ORA-12592: Network Session: Invalid NS packet format (likely marker packet) ---> OracleInternal.Network.NetworkException (0x00003130): ORA-12592: Network Session: Invalid NS packet format (likely marker packet)