.Net core 2.0 with oracle db connection

with current .Ora file we are able to connect in .net 2.0 and 3.5 and unable to connect with .net core 2.0 , whether we need to modify the .ora file compared to old one. please tell the steps

OracleInternal.Network.NetworkException (0x00002F7A): ORA-12154: TNS:could not resolve the connect identifier specified at OracleInternal.Network.AddressResolution..ctor(String TNSAlias, String instanceName) at OracleInternal.Network.OracleCommunication.DoConnect(String tnsDescriptor) at OracleInternal.ServiceObjects.OracleConnectionImpl.Connect(ConnectionString cs, Boolean bOpenEndUserSession, OracleConnection connRefForCriteria, String instanceName) at OracleInternal.ConnectionPool.PoolManager3.Get(ConnectionString csWithDiffOrNewPwd, Boolean bGetForApp, OracleConnection connRefForCriteria, String affinityInstanceName, Boolean bForceMatch) at OracleInternal.ConnectionPool.OraclePoolManager.Get(ConnectionString csWithNewPassword, Boolean bGetForApp, OracleConnection connRefForCriteria, String affinityInstanceName, Boolean bForceMatch) at OracleInternal.ConnectionPool.OracleConnectionDispenser3.Get(ConnectionString cs, PM conPM, ConnectionString pmCS, SecureString securedPassword, SecureString securedProxyPassword, OracleConnection connRefForCriteria) at Oracle.ManagedDataAccess.Client.OracleConnection.Open() at TodoApi.Startup.b__5_0(HttpContext context) in D:\Samples\TodoApi\TodoApi\Startup.cs:line 68}

Put correct configuration in tns .ora file inside app client folder or check your connection string in json file.