# SQL Server Transport Upgrade Version 3 to 4



## TransactionScope

[TransactionScope transaction mode](/transports/sql/transactions.md#transaction-scope) is not available in .NET Core 2.0 because the implementation of `SqlConnection` does not support enlisting in an ambient transaction.

To run the upgraded project on .NET Core the transport needs to be switched to one of the native transactions modes. Consider using the [Outbox](/nservicebus/outbox/index.md) to maintain the same *exactly-once processing* guarantees.

> [!NOTE]
> Transaction scope is supposed to be supported by `SqlConnection` in future versions of .NET Core.


## Multi-instance mode

The multi-instance mode has been deprecated in Version 4. So the following is no longer supported:

```csharp
var transport = endpointConfiguration.UseTransport<SqlServerTransport>();
transport.EnableLegacyMultiInstanceMode(async address =>
{
    var connectionString = address.StartsWith("RemoteEndpoint")
        ? "Data Source=SQL; Database=RemoteEndpoint; Integrated Security=True"
        : "Data Source=SQL; Database=ThisEndpoint; Integrated Security=True";
    var connection = new SqlConnection(connectionString);
    await connection.OpenAsync();
    return connection;
});
```

NServiceBus topologies with queues distributed between multiple catalogs hosted in a single instance of SQL Server can now be configured using multi-catalog [addressing](/transports/sql/addressing.md):

```csharp
var transport = endpointConfiguration.UseTransport<SqlServerTransport>();
transport.ConnectionString("Data Source=SQL; Database=ThisEndpoint; Integrated Security=True");
transport.UseCatalogForEndpoint(
    endpointName: "RemoteEndpoint",
    catalog: "RemoteEndpoint");
```

If catalogs are hosted in different instances of SQL Server, use [NServiceBus.MessagingBridge](/nservicebus/bridge/index.md) to construct a bridge. The [multi-instance sample](/samples/bridge/sql-multi-instance/index.md) demonstrates this approach.