We may have found a defect in mssql 2017 related to starting a transaction (BEGIN TRAN) only within a try-catch block invalidating the transaction.

Author: lizbaron

Experiments/Experiments.ssmssqlproj

@@ -66,6 +66,12 @@
           <AssociatedConnUserName />
           <FullPath>LIKE4000.sql</FullPath>
         </FileNode>
+        <FileNode Name="MSSQL Defect Try-Catch Invalidates Transaction.sql">
+          <AssociatedConnectionMoniker />
+          <AssociatedConnSrvName />
+          <AssociatedConnUserName />
+          <FullPath>MSSQL Defect Try-Catch Invalidates Transaction.sql</FullPath>
+        </FileNode>
         <FileNode Name="NameResolutionResearch.sql">
           <AssociatedConnectionMoniker />
           <AssociatedConnSrvName />

Experiments/MSSQL Defect Try-Catch Invalidates Transaction.sql

@@ -0,0 +1,20 @@
+PRINT 'No TRY...CATCH:';
+EXEC ('BEGIN TRAN');
+SELECT XACT_STATE() AS [XACT_STATE()],@@TRANCOUNT AS [@@TRANCOUNT];
+GO
+IF(XACT_STATE()<>0)ROLLBACK;
+GO
+
+
+
+GO
+PRINT 'In TRY...CATCH:';
+BEGIN TRY
+EXEC ('BEGIN TRAN');
+END TRY
+BEGIN CATCH
+END CATCH;
+SELECT XACT_STATE() AS [XACT_STATE()],@@TRANCOUNT AS [@@TRANCOUNT];
+GO
+IF(XACT_STATE()<>0)ROLLBACK;
+GO