string connectionString = string.Format(@"Provider=Advantage OLE DB Provider;data source={0}; Advantage Server Type=ADS_REMOTE_SERVER;SecurityMode=ADS_IGNORERIGHTS;TableType=ADS_CDX;Locking=ADS_COMPATIBLE_LOCKING;", folderPath);

System.Data.OleDb.OleDbException: Invalid path or file name.
at System.Data.OleDb.OleDbConnectionInternal..ctor(OleDbConnectionString constr, OleDbConnection connection)
at System.Data.OleDb.OleDbConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningObject)
at System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup)
at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
at System.Data.OleDb.OleDbConnection.Open()

string connectionString = string.Format(@"Provider=vfpoledb.1;data source={0}; TableType=vfp;", folderPath);

System.Data.OleDb.OleDbException: Invalid path or file name