Don't be so quick to blame the service or MSDTC when you see the error "Communication with the underlying transaction manager has failed."

Symptom:

An error message that reads something like:

System.Transactions.TransactionManagerCommunicationException: Communication with the underlying transaction manager has failed. ---> System.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.

Solutions:

"Check your firewall settings" is what you will find in almost all forum posts and on MSDN. You need port 135 open bi-directionally for RPC's end point mapper (EPM). You also need ports 1024-5000 open bi-directionally if you have not specified your own port settings for RPC in the registry. If you have your own ports specified in the registry, then those need to be open bi-directionally.

WHAT ?!? It may also be your code causing the issue. If you are using TransactionScope, you have to be mindful of every method called within the using braces. Looking at the code below, you will see two service calls and a seemingly innocuous ShouldContinue() method checking to see if the second operation should be called.

using (TransactionScope scope = new TransactionScope())

using (MyServiceClient proxy = new MyServiceClient())

{

       proxy.DoOperationOne(someID);

      

       if (ShouldContinue()) // uh, oh! What if this has an ADO.NET connection that is opened and closed inside it?

       {

               proxy.DoOperationTwo(someOtherID);

       }

}

If ShouldContinue() opens and closes an SqlConnection, the TransactionScope object has no means by which to commit or rollback this part of the transaction. This will cause the error "Communication with the underlying transaction manager has failed."

1. If you do not need to results of DoOperationOne() to feed ShouldContinue(), then do that logic before the TransactionScope using block.

2. If you do need the result of DoOperationOne() to feed ShouldContinue(), then you can wrap the internals of ShouldContinue() with a TransactionScope using block specifying TransactionScopeOption.Suppress. This will not add the resource access contained within the block to the ambient transaction.

3. Use an intelligent data access library like Enterprise Library that manages your connections for you. It won't close the connection if enlisted in a transaction.

Look at your code before you involve your network dudes. This is more common when integrating legacy code with new service calls.