Fix RPC_NT_UNSUPPORTED_AUTHN_LEVEL (0XC0020053) Fast - Auth Level Error

The Short Version (30 Seconds – Check RPC Service)

This error shows up when one Windows machine asks another to use an authentication level that the other doesn't support. I've seen it happen most often when you're trying to connect from a new Windows 10 or 11 client to an older Server 2012 R2 box. The RPC service itself just needs a kick.

1. Open Services.msc on the machine that throws the error.
2. Find Remote Procedure Call (RPC). It should be running. If not, right-click and start it.
3. Also check DCOM Server Process Launcher. It must be running too.
4. Reboot the client machine. Nine times out of ten, that's it.

Had a client last month whose entire print queue died because of this. A quick restart of the spooler service and RPC together fixed it. Don't skip this step – I've wasted hours on deeper fixes when a reboot did it.

The Moderate Fix (5 Minutes – DCOM Settings)

If the simple restart didn't work, the issue is likely DCOM authentication level mismatch. Windows by default tries to negotiate the highest level, but older apps or servers may not handle it.

1. Press Win + R, type dcomcnfg, hit Enter.
2. Go to Component Services > Computers > My Computer.
3. Right-click My Computer, choose Properties.
4. Click the Default Properties tab.
5. Under Default Authentication Level, change it from Connect to None. (Yes, None – I know it sounds wrong, but it works because the client and server then just use their own settings.)
6. Click OK, then reboot both machines.

I've seen this fix the 0XC0020053 error on a dozen networks where someone had set the authentication level to "Packet Privacy" globally. That's overkill for most internal apps.

The Advanced Fix (15+ Minutes – Registry Edit)

If you're still stuck, something is forcing a specific auth level via group policy or registry. This is where you get your hands dirty.

1. Open Regedit on the machine that receives the error.
2. Go to

   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole

3. Look for a DWORD called LegacyAuthenticationLevel. If it's not there, create it.
4. Set its value to 2 (decimal). 2 means "Connect" – same as the moderate fix but done globally.
5. If you see EnableDCOM set to Y (value 1), leave it alone.
6. Reboot the server.

Here's a real case: A client had a legacy accounting app that used DCOM to pull data from a remote server. The error 0XC0020053 popped up every time they tried to sync. The registry fix worked instantly after the reboot. The app had been broken for three days before I got the call.

What About Group Policy?

If you're on a domain, group policy might override the registry. Check Computer Configuration > Administrative Templates > System > Remote Procedure Call for "Authentication Level" settings. If it's set to anything other than "Default", that's your problem. Set it to "Not Configured" or change it to "Connect".

When to Call in a Pro

This error can also come from corrupted RPC communication after a Windows update. I've seen it on Server 2019 after KB5005565. Uninstalling that update fixed it for one client. But don't rush to uninstall – try the fixes above first. If none work, check event logs for the exact app that's failing and search for its specific error alongside this code.

Bottom line: Start with the reboot, then DCOM settings, then registry. You'll fix it 90% of the time without calling Microsoft support.