I'm trying to connect to Oracle 12.2.0 from Visual Studio 2017 using System.Data.OracleClient provider and get ORA-12638 error.
I can connect to database from sqldeveloper or using Oracle.ManagedDataAccess.Client provider.
My connection string is: name="ConnectionString" connectionString="DATA SOURCE=xxx.xx.xx.xxx:xxxxx/xx;PASSWORD=yyyy;Persist Security Info=True;User ID=yyyyy;Unicode=True" providerName="System.Data.OracleClient"
I have System.Data.OracleClient in References. I change SQLNET.AUTHENTICATION_SERVICES to (NONE) in sqlnet.ora.
Any ideas what might be wrong or where should I start looking?