Fix ALPC Port Closed Error 0XC0000700

Quick Answer for Advanced Users

Kill the hanging process holding the ALPC port using taskkill /f /im [processname].exe or restart the associated service. If it's LSASS, reboot ASAP.

What's Actually Happening Here

I see this error most often on Windows 10 and 11 machines after a service or driver crashes without properly closing an ALPC (Advanced Local Procedure Call) port. You'll get the 0XC0000700 code in Event Viewer or as a popup when an app tries to communicate over an already-closed port. One client last month had it after their third-party antivirus killed a Windows service mid-stream. The port stays locked until the process holding it actually dies.

Step-by-Step Fix

Identify the culprit. Open Event Viewer (eventvwr.msc), look under Windows Logs > System. Filter for source 'ALPC' or error 0XC0000700. Note the process name (usually something like svchost.exe with a specific PID).
Kill the process. Open Task Manager or run tasklist in Command Prompt as admin. Find the PID from step 1. Then run:
```
taskkill /f /pid [PID number]
```
If it's a system process like lsass.exe, you can't kill it — skip to step 3.
Restart the service. If killing the process fails, restart the related service. Common ones: RPC Endpoint Mapper, DCOM Server Process Launcher. Run:
```
net stop [servicename] && net start [servicename]
```
For example: net stop RpcSs && net start RpcSs.
Reboot as last resort. When nothing else works, a full restart clears all ALPC handles. Run shutdown /r /t 0.

Alternative Fixes If the Main One Fails

Run SFC and DISM. Corrupted system files can cause ALPC ports to close prematurely. Open Command Prompt as admin and run:
```
sfc /scannow
```
then
```
DISM /Online /Cleanup-Image /RestoreHealth
```
.
Check for driver issues. Specifically, third-party drivers for VPNs, firewalls, or AV software. Disable them one by one until the error stops. Had a client whose Malwarebytes driver was the cause.
Repair the Windows Registry. ALPC port settings are in HKLM\SYSTEM\CurrentControlSet\Services\ALPC. Only touch this if you're comfortable — one wrong edit can break RPC entirely.

Prevention Tip

Stop random service restarts during business hours. If you've got a server or workstation that people rely on, schedule service restarts during off hours. Also, keep your drivers and antivirus up to date — outdated ones are the #1 cause of ALPC port closures in my experience.

Pro tip: If the error happens after a Windows update, roll back the update via Settings > Update & Security > View update history > Uninstall updates. That fixed it for a whole office last year.