CMD terminal windows constantly flashing / popping up on Windows 11

[alenguav]

Issue Type

Browser Issue

Operating System

Windows

Description of the bug

Since installing BrowserOS on Windows 11, I have been experiencing persistent, rapid CMD / terminal windows popping up and automatically closing immediately after.

These flashing terminal windows appear frequently in the background, disrupting focus while using other applications.

Steps to Reproduce

1. Install BrowserOS on Windows 11.
2. Run BrowserOS and work in other tasks
3. Observe the desktop. A blank command prompt window (cmd.exe) will flash briefly on the screen and close itself every few minutes.

Screenshots / Videos

No response

BrowserOS Version

No response

Additional Context

No response

[hirosatosou]

This may well be the same root cause as #2072.

BrowserOS launches native messaging hosts through cmd.exe rather than invoking the executable directly. Upstream Chromium stopped doing this in M113 (2023); BrowserOS at M148 still does it by default. Those intermediate cmd.exe processes are a plausible source of the flashing windows — on my machine they were spawned in bursts every few minutes, which matches your description.

Same cause, second symptom: because the cmd.exe exits immediately, the native messaging host it spawned is orphaned at birth. When the extension later closes the port, the browser terminates the process it spawned — the already-dead cmd.exe — so the host is never terminated and accumulates. On this machine that reached 1,196 orphaned processes / 20.3 GB / 318k handles in 21 hours.

Workaround — force direct launch via policy, then restart BrowserOS:

# Requires elevation: HKCU\SOFTWARE\Policies is writable only by Administrators
New-Item -Path 'HKCU:\SOFTWARE\Policies\Chromium' -Force | Out-Null
New-ItemProperty -Path 'HKCU:\SOFTWARE\Policies\Chromium' `
  -Name 'NativeHostsExecutablesLaunchDirectly' -Value 1 -PropertyType DWord -Force | Out-Null

BrowserOS reads policies from the unbranded Chromium root (SOFTWARE\Policies\Chromium) — there is no SOFTWARE\Policies\BrowserOS. After restarting the browser, the cmd.exe step disappeared from the launch chain and hosts started exiting normally (before: 0 of 1,001 ever exited; after: 3 of 4).

Caveat: this only applies if you have an extension that uses native messaging (password managers, hardware token bridges, etc.). I confirmed the cmd.exe step only for that path. If your CMD windows appear with no such extension installed, they are coming from something else and this won't help — but it costs nothing to try, and the change is reversible:

Remove-ItemProperty -Path 'HKCU:\SOFTWARE\Policies\Chromium' -Name 'NativeHostsExecutablesLaunchDirectly'

One side effect worth knowing: setting any policy makes Chromium show "Managed by your organization" in the menu. Cosmetic only.