The 30-Second Fix: Restart RPC Services
Nine times out of ten, this error shows up because the Remote Procedure Call (RPC) service or one of its dependencies has stopped. It happens after a botched Windows update, a third-party service killed it, or the machine just decided to take a nap. Don't overthink this yet.
Open an admin Command Prompt and run:
net stop rpcss && net start rpcss
net stop dcomlaunch && net start dcomlaunchIf those services are already running, restart them anyway. It forces a clean start on the RPC endpoint mapper, which is usually the root cause.
Still broken? Move on to the next step.
The 5-Minute Fix: Check DCOM and Firewall
The RPC endpoint mapper listens on port 135. If that port is blocked—by Windows Firewall, a third-party firewall, or router ACLs—you'll get 0X000006B3. This happens a lot with remote management tools or when someone tightened security after a compliance audit.
First, verify the port is listening locally:
netstat -an | findstr :135You should see LISTENING on the local address. If not, the RPC mapper is dead—go back to the first fix.
If it's listening, check the firewall. On the target machine, run:
netsh advfirewall firewall add rule name="RPC Endpoint Mapper" dir=in action=allow protocol=TCP localport=135That opens the port for all profiles. For a more secure setup, restrict it to specific remote IPs, but for immediate relief this works.
Also, check the DCOM configuration. Open dcomcnfg from Run (Win+R). Go to Component Services → Computers → My Computer. Right-click, select Properties, and look at the Default Properties tab. Make sure Enable Distributed COM on this computer is checked. If it's not, that's your culprit. Re-enable it and reboot the machine—yes, a reboot is necessary, I know it's annoying.
The 15+ Minute Fix: Re-register RPC and Check Permissions
If you're still here, the simple fixes didn't cut it. This is where we dig deeper. The error can also be triggered by corrupted RPC registration or broken security descriptors.
First, re-register the RPC runtime libraries. Open an admin Command Prompt and run:
regsvr32 /s rpcrt4.dll
regsvr32 /s rpcss.dllThen restart the services again. If that doesn't do it, check the RPC service dependencies. The Remote Procedure Call (RPC) service depends on DCOM Server Process Launcher and RPC Endpoint Mapper. If any of those are disabled, you're stuck. Go to services.msc, find Remote Procedure Call (RPC), and double-click it. Under the Dependencies tab, make sure all listed services are set to Automatic and running.
I've also seen this error when the local Everyone group loses permission on the RPC endpoint mapper. This happens after domain policy changes. To check, open dcomcnfg → Component Services → Computers → My Computer, right-click, Properties, and go to COM Security. Under Access Permissions, click Edit Default. Make sure Everyone has Local Access and Remote Access allowed. If not, add them.
Finally, if this only happens when connecting from a remote machine, check the Windows Management Instrumentation (WMI) service. RPC and WMI are joined at the hip. If WMI is stopped or corrupted, you'll get this exact error when trying remote management commands like wmic or Get-WmiObject. Restart WMI with:
net stop winmgmt && net start winmgmtThat usually clears up lingering issues.
When to Give Up and Reboot
Honestly, after all this, if it's still not working, it's time to look at the bigger picture. Check the System Event Log for any RPC-related errors—they'll point to a specific service or a corrupted driver. If nothing shows up, a full reboot of the server—not just the services—resolves it. I've seen this error hang around through three service restarts, only to vanish after a proper shutdown and power-on.
One last thing: don't bother disabling the firewall entirely. That's a knee-jerk fix that creates more problems. The specific port rule works fine. If you're in a domain environment, also verify that the Remote Procedure Call (RPC) firewall rule isn't overridden by a group policy—this happens more often than you'd think.
That's it. If you're still stuck after trying all three steps, you're dealing with something specific to your environment—check for recent changes like new security software or a network change. But 99% of the time, one of these fixes gets you back up.