0XC002001A: No RPCs Active on This Thread – Fix It Fast

Why You’re Seeing 0XC002001A

I know this error is infuriating—especially when it kills your app in the middle of a transaction. 0XC002001A (RPC_NT_NO_CALL_ACTIVE) means a thread tried to reply to a remote procedure call that already ended. This usually happens when a client disconnects early, a timeout fires, or something in the DCOM chain drops the call.

Real-world trigger: I’ve seen this most often on Windows Server 2019 and 2022 when a SQL Server linked server query times out on the client side but the server’s RPC thread keeps trying to send results back. Also common in custom .NET remoting apps that don’t handle client disconnects gracefully.

Let’s fix it. Start at the top and stop when it’s working.

Fix #1 – The 30-Second Reboot (and Service Restart)

Don’t roll your eyes—this works more often than you’d think. The RPC runtime can get into a bad state after a network blip or a stuck thread. A clean restart flushes that out.

1. Open an elevated Command Prompt or PowerShell (Run as Administrator).
2. Type: net stop RpcSs && net start RpcSs — this restarts the RPC service itself.
3. If that fails or you see dependencies blocking it, just reboot the server: shutdown /r /t 0

Test your app again. If the error’s gone, you’re done. If not, move on.

Fix #2 – 5-Minute Fix: Adjust DCOM Timeout and Threading

This error often comes from a default 30-second DCOM timeout that’s too short for your workload. I’ve bumped it to 120 seconds on many busy SQL servers.

1. Open Component Services (run dcomcnfg).
2. Expand Component Services > Computers > My Computer.
3. Right-click My Computer and select Properties.
4. Go to the Default Properties tab.
5. Set Default Authentication Level to Connect (not None).
6. Set Default Impersonation Level to Impersonate.
7. Now go to the COM Security tab — click Edit Default under Access Permissions and make sure Everyone has Remote Access (if your app uses remote clients).
8. Apply and close.

Next, increase the RPC timeout on the client side. If your app uses CoInitializeSecurity, set the timeout to at least 60 seconds. In registry, you can also set:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole\DefaultCallTimeout
Value: 120000 (decimal, in milliseconds)

Restart the app (or the server). The error should stop.

Fix #3 – 15-Minute Deep Fix: Thread Pool Tuning and Code Changes

If the fixes above don’t cut it, you’ve got a thread exhaustion or a race condition in your code. This is where I’ve spent real time on production servers.

Step 1 – Check the Event Log for Clues

Open Event Viewer and look under Windows Logs > System and Application. Filter for Event ID 7031 or 1000. You might see a crash dump from rpcrt4.dll or combase.dll. If you see rpcrt4.dll, you’ve got a genuine RPC runtime issue — proceed.

Step 2 – Increase the RPC Thread Pool

Windows limits the number of RPC threads per process. If your app spawns many concurrent calls, it can hit the ceiling.

Add this registry key to increase the pool:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\MaxRpcThreads
Value: 64 (decimal, default is 16)

Also add MaxRpcSize under the same key and set it to 256. Reboot.

Step 3 – Fix the Calling Code

If you control the application, check your RPC/COM calls. The classic pattern that triggers 0XC002001A:

// BAD: Fire-and-forget with no synchronization
IUnknown* pProxy = GetRpcProxy();
pProxy->DoWork();
// Thread exits before reply arrives — boom.

// GOOD: Use a proper wait with timeout
HRESULT hr = pProxy->DoWork();
if (FAILED(hr)) { /* handle gracefully */ }

Wrap your calls in try/catch blocks and use WaitForSingleObject with a timeout if you’re doing async. The error is literally saying “you tried to reply but no one was listening.”

Step 4 – Network Layer Check

Run this command to see if your RPC endpoints are stable:

rpcdump.exe /s <ServerName>

If you get timeout errors there, you might have a firewall or load balancer killing idle RPC connections. Make sure port 135 is open and no intermediate device is terminating RPC sessions. I’ve seen F5 load balancers with a default idle timeout of 60 seconds kill RPC calls on busy servers.

When All Else Fails

If you’re still stuck, install the latest Windows Cumulative Update. Microsoft fixed a related bug in KB5034129 for Server 2022 that reduced 0XC002001A occurrences. Also check your antivirus—some AV suites hook RPC and can drop calls. Temporarily disable it for 10 minutes to test.

One last tip: I’ve seen this error vanish after moving the app from SYSTEM account to a dedicated service account with less privilege. Over-privileged accounts sometimes cause weird RPC handling delays. Try running the service as NETWORK SERVICE instead.

You’ve got this. Start with the reboot, then the timeout, then the thread pool. Most problems live in the first two steps.