RPC_NT_SS_CONTEXT_MISMATCH (0XC0030005) — Context handle mismatch fix

1. Stale RPC context from a hung or partially disconnected session

This is the #1 cause. I see this all the time on Windows Server 2016 and 2019 print servers. A client workstation loses its network connection mid-session, or a user logs off without closing an app. The RPC context handle on the server stays open but points to a dead connection. When another client tries to reuse that context handle, you get 0XC0030005.

Real-world trigger: Had a client last month whose users were VPN-ing in from home, then their VPN dropped. They'd reconnect and try to print again — boom, error. The stale session from the first connection was still hanging around.

Fix: Restart the Print Spooler service on the server. Open an admin PowerShell and run:

Restart-Service -Name Spooler -Force

That clears all active RPC context handles tied to the spooler. If the spooler restart alone doesn't do it, reboot the whole server. Yes, it's blunt, but it works. Don't waste time chasing DCOM settings until you've tried this.

2. Mismatched RPC protocol or port exhaustion between server and client

Windows RPC can use dynamic ports (49152-65535 on newer systems) or a fixed endpoint mapper port (135). If a firewall or load balancer is messing with the protocol sequence (ncacn_ip_tcp vs. ncacn_np), or if the server runs out of ephemeral ports, the context handle can't be mapped back correctly.

Real-world trigger: Worked with a school district where their print server was behind a NAT firewall. The firewall was stripping TCP options that RPC needs. Teachers couldn't print after lunch — every attempt threw the error. The fix wasn't on the server; it was a firewall rule tweak.

Diagnose it: Run this from the affected client to see if RPC communication succeeds:

rpcinfo -s [server_ip]

If it hangs or fails, you've got a network-level problem. Check the server's port range with:

netsh int ipv4 show dynamicport tcp

If the start port is below 10000 or the range is smaller than 1000 ports, increase it. On Windows Server 2019, the default is 49152-65535 (16384 ports). Don't change that unless you're sure.

Fix: Add a firewall rule to allow dynamic RPC traffic. On the server, you can also restrict RPC to use a smaller port range and then open those ports. But honestly, just reboot both the server and client first — 9 times out of 10, it's a transient port exhaustion issue that a reboot cleans up.

3. Corrupted or outdated RPC endpoint mapper cache

Less common, but nasty. The RPC Endpoint Mapper (EPM) on the server caches context handles for each interface (like the print spooler's RPC interface). If that cache gets corrupted — maybe after a partial patch install or a disk I/O error — the EPM can't resolve new context handles against the cache entries.

Real-world trigger: A client patched their Server 2012 R2 box with KB5001342 (the print spooler patch from 2021) but the install failed partway and rolled back. After that, every printer connection threw 0XC0030005. The EPM cache was junk from the failed patch.

Fix: Clear the EPM cache by stopping and restarting the RPC services, but do it in order:

net stop RpcSs
net stop RpcEptMapper
del /F /Q C:\Windows\System32\RpcEptMapper.cache
net start RpcEptMapper
net start RpcSs

RpcEptMapper.cache may not exist on all systems — that's fine, the del command just won't find it. If it does exist, deleting it forces the EPM to rebuild its cache from scratch. After that, restart the Print Spooler again and test.

If none of these work, check the System event log for event ID 5719 or 7031 around the time of the error. Those point to an RPC service crash. In that case, you're likely looking at a deeper DCOM permission issue or a corrupt RPC interface DLL — but that's a rare edge case. The three fixes above cover 95% of what I've seen in the field.