Why doesn't TransactionScope work with Entity Framework?
.net, c#, entity-framework, transactions, transactionscope
Solution
Your MS-DTC (Distributed transaction co-ordinator) is not working properly for some reason. MS-DTC is used to co-ordinate the results of transactions across multiple heterogeneous resources, including multiple sql connections.
Take a look at this link for more info on what is happening.
Basically if you make sure your MS-DTC is running and working properly you should have no problems with using 2 ADO.NET connections - whether they are entity framework connections or any other type.
Problem
See the code below. If I initialize more than one entity context, then I get the following exception on the 2nd set of code only. If I comment out the second set it works. {"The underlying provider failed on Open."} Inner: {"Communication with the underlying transaction manager has failed."} Inner: {"Error HRESULT E_FAIL has been returned from a call to a COM component."} Note that this is a sample app and I know it doesn't make sense to create 2 contexts in a row. However, the production code does have reason to create multiple contexts in the same `TransactionScope`, and this cannot be changed. Edit Here is a previous question of me trying to set up MS-DTC. It seems to be enabled on both the server and the client. I'm not sure if it is set up correctly. Also note that one of the reasons I am trying to do this, is that existing code within the `TransactionScope` uses ADO.NET and Linq 2 Sql... I would like those to use the same transaction also. (That probably sounds crazy, but I need to make it work if possible). How do I use TransactionScope in C#? Solution Windows Firewall was blocking the connections to MS-DTC. ``` using(TransactionScope ts = new System.Transactions.TransactionScope()) { using (DatabaseEntityModel o = new DatabaseEntityModel()) { var v = (from s in o.Advertiser select s).First(); v.AcceptableLength = 1; o.SaveChanges(); } //-> By commenting out this section, it works using (DatabaseEntityModel o = new DatabaseEntityModel()) { //Exception on this next line var v = (from s1 in o.Advertiser select s1).First(); v.AcceptableLength = 1; o.SaveChanges(); } //-> ts.Complete(); } ```