The System.Transaction assembly is not part of the .net core framework at the moment (see https://github.com/dotnet/corefx/issues/2949). In my application (asp.net core mvc)
Update 2 .NET Core 2.0 is out now. You can use this API. See https://docs.microsoft.com/en-us/dotnet/api/system.transactions.transactionscope?view=netcore-2.0
Update System.Transactions will be available in NET Core 2.0. See https://github.com/dotnet/core/blob/master/roadmap.md for details on upcoming releases.
Original answer
System.Transactions (or ambient transactions) is not implemented in .NET Core 1.0.0 but may be implemented in future versions.
You can work around this by using explicit transactions.
using (var connection = new SqlConnection(connectionString))
{
connection.Open();
using (var transaction = connection.BeginTransaction())
{
// transaction.Commit();
// transaction.Rollback();
}
}