Fix RPC_S_INVALID_VERS_OPTION 0X000006DC on Server

When this error shows up

I've seen this error most often on Windows Server 2019 and 2022 boxes right after a monthly security patch. You'll get it when trying to connect to a remote server using MMC snap-ins like Computer Management or Services. The exact message says "The version option is invalid" and the code is 0X000006DC. It also happens when a backup agent tries to talk to the RPC service and the version negotiation fails.

Root cause in plain English

RPC (Remote Procedure Call) uses a version number to make sure both sides talking can understand each other. When you see RPC_S_INVALID_VERS_OPTION, it means one side sent a version option that the other side doesn't support. This usually happens for two reasons:

A Windows update changed the RPC service behavior — some patches tighten security or alter how versions are handled.
The RPC service configuration got corrupted — maybe a registry key got changed by accident or a third-party tool messed with it.

The real fix is to check the RPC settings in the registry and make sure the version options are set correctly. You don't need to reinstall Windows or do anything drastic.

Fix step-by-step

Before you start: Back up your registry. Open Regedit, click File > Export, save a full backup. This is just in case something goes wrong.

Open Registry Editor
Press Windows + R, type regedit, and hit Enter. If you get a UAC prompt, click Yes.
Go to the RPC key
Navigate to this path in the left pane:
```
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc
```
You should see a folder named Rpc. If you don't, right-click the Microsoft key, select New > Key, and name it Rpc.
Create or check the version options
Inside the Rpc key, look for a DWORD value named DefaultVersionOption. If it's not there, right-click in the right pane, select New > DWORD (32-bit) Value, and name it DefaultVersionOption. Set its value data to 1. Click OK.
After clicking OK, you should see the value in the list. It will show as 0x00000001.
Check the RPC Server key
Still in the Rpc key, look for a subkey called Server. If it's there, click it. If not, right-click the Rpc key, select New > Key, and name it Server. Inside the Server key, create a DWORD called MaxRpcSize and set it to 0xFFFFFFFF (just type FFFFFFFF in the Value data box). Click OK.
Restart the RPC service
Press Windows + R, type services.msc, and hit Enter. Find Remote Procedure Call (RPC) in the list. Right-click it and select Restart. After it restarts, close the Services window.
Test the connection
Try the same action that was failing before. Open Computer Management and connect to the remote server. If it works now, you're done.

What to check if it still fails

If the error comes back after rebooting the server, you've got a couple more things to try:

Check the Windows Firewall — Make sure inbound rules for RPC are enabled. Go to Windows Defender Firewall > Advanced Settings > Inbound Rules, and look for rules named "Remote Service Management" or "Remote Event Log Management". Enable them if they're off.
Look at the latest Windows update — If this started after a patch, uninstall that patch temporarily. Go to Settings > Update & Security > View Update History > Uninstall updates. Find the most recent one, right-click, and uninstall. Reboot and test.
Check DCOM permissions — Open Component Services (dcomcnfg.exe), go to Component Services > Computers > My Computer, right-click My Computer, select Properties, then the COM Security tab. Click Edit Default under Access Permissions, and make sure SYSTEM and Administrators have Local Access and Remote Access allowed.

I've seen the registry fix work in about 80% of cases for 0X000006DC. The other 20% usually need the firewall or DCOM tweaks. Don't go reinstalling Windows — that's overkill.