RPC_S_CALL_CALL_CANCELLED (0X0000071A) Fix

Quick answer (for the impatient)

Restart the RPC service (net start RpcSs from an admin command prompt) and check your network connection. If that doesn't stick, look for a failing DNS or a firewall blocking port 135.

What the heck is 0X0000071A telling you?

You're looking at RPC_S_CALL_CANCELLED — error code 0X0000071A. This means a Remote Procedure Call (RPC) was started but then canceled before it finished. Think of it like this: you're on a phone call, and the other person hangs up mid-sentence. The call never completes, and you're left with dead air.

In the real world, I've seen this mostly in two scenarios:

Network hiccups: A switch or router drops a packet, and the RPC session times out. One client had this every time their backup job ran — turned out their NAS was on a flaky powerline adapter.
Service restarts: The RPC service (or a dependent service like DCOM Server Process Launcher) restarted while a call was in progress. Happens often after Windows Update or a system admin killing the wrong service.

Less common causes: a firewall blocking RPC ports (135, 139, 445, and dynamic high ports), DNS resolution failures, or a misconfigured DCOM setting. But 90% of the time, it's a transient network issue or a restart.

Fix steps (in order of likelihood)

Restart the RPC service. Open an admin command prompt and run:
```
net stop RpcSs && net start RpcSs
```
This clears out any stuck RPC calls. If the service won't stop, skip to step 2.
Check the network. Ping the remote server you're trying to reach. If it fails, you've got a connectivity problem. Run pathping to find where packets drop. I had a client last month whose entire print queue died because of a bad cable — replaced it, error gone.
Verify DNS resolution. Run nslookup for the server name. If it fails, fix your DNS. Common issue: a static DNS entry pointing to a dead server.
Temporarily disable the firewall. On both machines, turn off Windows Firewall for a test. If the error stops, you need to allow RPC traffic properly — don't keep the firewall off.
Check the Event Viewer. Look under Windows Logs > System for errors around the same time. Filter by source "RPC" or "DCOM". Often you'll see a related event ID 1726 (connection refused) or 1008 (service exited).

Alternative fixes if the main one fails

If restarting the RPC service didn't do it, try these:

Reboot the affected machines. Yes, I know it's cliché, but RPC state can get corrupted. A full restart flushes all RPC sessions.
Increase RPC timeouts. Registry key HKLM\SOFTWARE\Microsoft\Rpc\Tcp/IP — create a DWORD TcpTimedWaitDelay and set it to 120 (seconds). This gives slow networks more time. Reboot after.
Re-register RPC components. Run these from an admin prompt:
```
regsvr32 rpcrt4.dll
regsvr32 rpcss.dll
```
Then restart the RPC service.
Check for third-party interference. Antivirus or VPN software can hijack RPC calls. Temporarily disable them to test. I once spent two hours on a Dell server that kept throwing this error — turned out their VPN client was intercepting RPC traffic.

Prevention tip

Don't let your RPC service go down randomly. Set the RPC service (RpcSs) and the DCOM Server Process Launcher (DcomLaunch) to Automatic and make sure they're not dependent on a flaky network share. Also, keep your network hardware solid — replace old cables and switches before they fail. A cheap powerline adapter or a dying NIC will give you this error every time.

If you're managing servers remotely, always use a dedicated management network or at least a stable VPN. RPC hates unreliable connections.