Fixing RPC_NT_SS_CONTEXT_DAMAGED 0XC0030006 on Windows Server

Quick Answer

Restart the RPC service (net stop RpcSs && net start RpcSs) and flush the RPC endpoint mapper cache (rpcdump /flush). If that doesn't stick, check for a misbehaving third-party driver or a firewall killing idle RPC connections.

What's Going On?

Error 0XC0030006 means the RPC runtime lost track of the context handle — basically the server side of an RPC call changed or disappeared while the client was still talking to it. This happens when a service crashes, a driver reloads unexpectedly, or the RPC endpoint mapper recycles its state. I've seen it most often on servers running backup agents (like Veeam or CommVault) that hook into RPC, or after a Windows Update that didn't fully restart all RPC-dependent services. The error is common in clustered environments where failover can orphan RPC handles.

Step-by-Step Fix

1. Identify the failing application – Check the Application and System event logs for the source of the call. Look for Event ID 5719 (RPC connection failure) or 1000 (application error) near the timestamp of the error. This tells you which process or service triggered it.
2. Restart the RPC Endpoint Mapper – Open an elevated command prompt and run:
   net stop RpcSs && net start RpcSs
   Then restart RPC Locator:
   net stop RpcLocator && net start RpcLocator
   This flushes all cached context handles. You might need to restart dependent services (like Netlogon, Server, or Workstation) afterwards.
3. Clear the endpoint mapper cache – Download the rpcdump tool from Windows SDK or use a native command:
   rpcdump /flush
   If rpcdump isn't available, use PowerShell:
   Get-WmiObject -Class Win32_Service | Where-Object {$_.Name -like "*RPC*"} | Restart-Service
4. Check for port exhaustion – Run netstat -an | find ":135" to see if port 135 (RPC Endpoint Mapper) has a backlog of half-open connections. If you see many TIME_WAIT states, the culprit is likely a client that's not closing connections cleanly. Increase the dynamic port range with:
   netsh int ipv4 set dynamicport tcp start=49152 num=16384
5. Disable RPC over named pipes – If your environment uses firewalls or NAT, RPC over TCP might get corrupted. Set the registry key to force RPC over TCP only:
   HKLM\SOFTWARE\Microsoft\Rpc\NameService
   Create a DWORD RestrictDynamicPorts with value 1.

If the Error Persists

If restarting doesn't help, the root cause is probably a driver or service that's resetting the RPC connection mid-stream. Start with a clean boot to confirm:

1. Run msconfig, select Selective startup, uncheck Load startup items.
2. Restart and test. If the error disappears, enable drivers one by one. Common culprits: backup agents (Veeam, NetBackup), antivirus real-time scanners (especially McAfee or Symantec), and storage filters like iSCSI initiators.
3. Check for corrupted RPC proxy registrations. Run dcomcnfg, expand Component Services, Computers, My Computer, DCOM Config. Look for entries with a yellow triangle or missing CLSID. Delete or re-register them using regsvr32.

Prevention Tips

• Set RPC port ranges explicitly via Group Policy: Computer Configuration > Administrative Templates > Network > RPC > Set RPC Dynamic Port Range. Keep it limited to a known range (e.g., 50000-55000) and open those ports on your firewall. This prevents port exhaustion from random ephemeral ports.
• Monitor Event ID 5719 and 1000 systematically. I use scheduled tasks that email me when these appear. The error compounds quickly — one dropped handle can snowball into a full RPC outage.
• Patch Windows regularly. Microsoft fixed several handle-management bugs in Server 2019 post-KB5008212 and Server 2022 in KB5013633. If you're on an older build, that's your first suspect.