How do i enable MSTDC on sqlserver?

Question

Is that even a valid question? I have a .Net windows app that is using MSTDC and it throwing an exception:

System.Transactions.TransactionManagerCommunicationException: Network access for Distributed Transaction Manager (MSDTC) has been disabled. Please enable DTC for network access in the security configuration for MSDTC using the Component Services Administrative tool ---> System.Runtime.InteropServices.COMException (0x8004D024): The transaction manager has disabled its support for remote/network transactions. (Exception from HRESULT: 0x8004D024) at System.Transactions.Oletx.IDtcProxyShimFactory.ReceiveTransaction(UInt32 propgationTokenSize, Byte[] propgationToken, IntPtr managedIdentifier, Guid& transactionIdentifier, OletxTransactionIsolationLevel& isolationLevel, ITransactionShim& transactionShim)....

I follow the guide here to able MSTDC on the pc, on which the app is installed. But the error still occurs. I was wondering if this was a DB issue? And if so how can i resolve it?

Answer 1

MSDTC must be enabled on both systems, both server and client.
Also, make sure that there isn't a firewall between the systems that blocks RPC.
DTCTest is a nice litt app that helps you to troubleshoot any other problems.

Answer 2

Do you even need MSDTC? The escalation you're experiencing is often caused by creating multiple connections within a single TransactionScope.

If you do need it then you need to enable it as outlined in the error message. On XP:

• Go to Administrative Tools -> Component Services
• Expand Component Services -> Computers ->
• Right-click -> Properties -> MSDTC tab
• Hit the Security Configuration button

Answer 3

@Andrew Do I not need msdtc enabled for transactions to work?. Either way, multiple connections are not being made as far as im aware.

Iv already run those steps on the client PC, are you saying I should also do those steps on the database server?

Answer 4

@Dan,

Do I not need msdtc enabled for transactions to work?

Only distributed transactions - Those that involve more than a single connection. Make doubly sure you are only opening a single connection within the transaction and it won't escalate - Performance will be much better too.

Answer 5

I've found that the best way to debug is to use the microsoft tool called DTCPing

1. Copy the file to both the server (DB) and the client (Application server/client pc)
2. Start it at the server and the client
3. At the server: fill in the client netbios computer name and try to setup a DTC connection
4. Restart both applications.
5. At the client: fill in the server netbios computer name and try to setup a DTC connection

I've had my fare deal of problems in our old company network, and I've got a few tips:

• if you get the error message "Gethostbyname failed" it means the computer can not find the other computer by its netbios name. The server could for instance resolve and ping the client, but that works on a DNS level. Not on a netbios lookup level. Using WINS servers or changing the LMHOST (dirty) will solve this problem.
• if you get an error "Acces Denied", the security settings don't match. You should compare the security tab for the msdtc and get the server and client to match. One other thing to look at is the RestrictRemoteClients value. Depending on your OS version and more importantly the Service Pack, this value can be different.
• Other connection problems:
  • The firewall between the server and the client must allow communication over port 135. And more importantly the connection can be initiated from both sites (I had a lot of problems with the firewall people in my company because they assumed only the server would open an connection on to that port)
  • The protocol returns a random port to connect to for the real transaction communication. Firewall people don't like that, they like to restrict the ports to a certain range. You can restrict the RPC dynamic port generation to a certain range using the keys as described in How to configure RPC dynamic port allocation to work with firewalls.

In my experience, if the DTCPing is able to setup a DTC connection initiated from the client and initiated from the server, your transactions are not the problem any more.