MultipleActiveResultSets=True (MARS) and query throws an exception when transaction is promoted

[Dusan8080]

Describe the bug

Distributed transactions are turned on. Connection string has MultipleActiveResultSets=True.
It works with:

Microsoft.Data.SqlClient 2.1.2
System.Data.SqlClient.SqlInternalConnectionTds
ExecuteTransactionYukon

if (internalTransaction != null && internalTransaction.IsDelegated)
{
if (_parser.MARSOn)
{
tdsParserStateObject = _parser.GetSession(this);
flag = true;
}
else if (internalTransaction.OpenResultsCount != 0)
{
throw SQL.CannotCompleteDelegatedTransactionWithOpenResults(this);
}
}

It throws an exception with:
Microsoft.Data.SqlClient 2.1.3
Microsoft.Data.SqlClient.SqlInternalConnectionTds
ExecuteTransactionYukon

if (internalTransaction != null && internalTransaction.IsDelegated)
{
if (_parser.MARSOn)
{
stateObj = _parser.GetSession(this);
mustPutSession = true;
}
if (internalTransaction.OpenResultsCount != 0)
{
SqlClientEventSource.Log.TryTraceEvent("<sc.SqlInternalConnectionTds.ExecuteTransactionYukon|DATA|CATCH> {0}, Connection is marked to be doomed when closed. Transaction ended with OpenResultsCount {1} > 0, MARSOn {2}", base.ObjectID, internalTransaction.OpenResultsCount, _parser.MARSOn);
throw SQL.CannotCompleteDelegatedTransactionWithOpenResults(this, _parser.MARSOn);
}
}

Between versions 2.1.2 and 2.1.3 there is change from "else if" -> "if"

Did not find anything about breaking changes between versions in release notes. Any explanation?

[lcheunglci]

Thanks @Dusan8080 for bring this issue to our attention. We'll have a look at it soon.

[lcheunglci]

Hi @Dusan8080 , from inspecting the changes, it appears the change was to resolve this issue #980 from this PR #1023. Also, is your project running .NET Framework or .NET Core? Also, what version of .NET Core were you using? The fix also aligned the code to match the behavior between .NET Core and .NET Framework.

[Dusan8080]

Hi @lcheunglci, our project is running .NET Framework.