Codex (MS Store app) launches as background process only; no UI. Console shows disk cache `Access is denied (0x5)`

What version of the Codex App are you using (From “About Codex” dialog)?

26.226.1021.0

What subscription do you have?

Plus

What platform is your computer?

W11

What issue are you seeing?

Launching the Codex Windows (Microsoft Store/MSIX) app results in no visible window/UI.

• Clicking Codex in the Start Menu does nothing visually.
• Task Manager shows Codex running as a Background process (CPU/RAM usage present), but no foreground window appears (not on the taskbar, not visible on the desktop).
• Launching via AppsFolder shows the same behavior:

explorer.exe "shell:AppsFolder\OpenAI.Codex_2p2nqsd0c76g0!App"

The app appears to start, but UI never renders. Running the packaged executable directly from PowerShell produces Electron/Chromium disk cache errors (likely preventing UI initialization):

$pkg = Get-AppxPackage OpenAI.Codex
$exe = Join-Path $pkg.InstallLocation "app\Codex.exe"
& $exe

Console output excerpt:

[IpcRouterManager] Another router is active.
...
ERROR:net\disk_cache\cache_util_win.cc:25 Unable to move the cache: Access is denied. (0x5)
ERROR:net\disk_cache\disk_cache.cc:236 Unable to create cache
ERROR:gpu\ipc\host\gpu_disk_cache.cc:724 Gpu Cache Creation failed: -2

Other messages observed (may be optional tooling / not fatal, but included for completeness):

[host-provider] ... errorCode=ENOENT ... "spawn applied ENOENT"
[host-provider] ... errorCode=ENOENT ... "spawn brix ENOENT"

Additional context:

• The MSIX is installed and registered successfully (no install errors).
• The manifest shows a valid app entry point:
• Id: App
• Executable: app\Codex.exe
• EntryPoint: Windows.FullTrustApplication
• Microsoft Edge WebView2 Runtime is installed:
• Microsoft Edge WebView2 Runtime version 145.0.3800.70

What steps can reproduce the bug?

1. Install Codex Windows app from the Microsoft Store listing (ProductId 9PLM9XGG6VKS) — in my case installed via WinGet:

``powershell
winget install --id 9PLM9XGG6VKS -s msstore
``

1. Launch Codex from the Start Menu.

1. Observe:

• No UI/window appears.
• Task Manager shows Codex running as a Background process.

1. (Optional diagnostic) Launch via AppsFolder:

``powershell
explorer.exe "shell:AppsFolder\OpenAI.Codex_2p2nqsd0c76g0!App"
``
Result is the same (background process only, no UI).

1. (Optional diagnostic) Run the packaged EXE directly to capture console logs:

``powershell
$pkg = Get-AppxPackage OpenAI.Codex
$exe = Join-Path $pkg.InstallLocation "app\Codex.exe"
& $exe
``
Observe repeated Chromium/Electron cache errors:

• Unable to move the cache: Access is denied. (0x5)
• Unable to create cache
• Gpu Cache Creation failed

What is the expected behavior?

_No response_

Additional information

• Installed package identity:
• Name: OpenAI.Codex
• Version: 26.226.1021.0
• PFN: OpenAI.Codex_2p2nqsd0c76g0
• Store ProductId: 9PLM9XGG6VKS

• Hypothesis:
• Codex (Electron/Chromium) is failing early because it cannot create/move its disk/GPU cache due to Access denied (0x5).
• This can also be exacerbated by multiple instances using the same cache/user-data directory; the log line [IpcRouterManager] Another router is active. suggests a prior/stuck instance or a single-instance lock.

• Suggested direction for a fix:
• Log the full cache path being used at startup (so users/admins can fix ACLs).
• Add a fallback cache location if the default cache path is not writable.
• Detect “another router is active” and either bring the existing window to the foreground or exit cleanly with a user-facing error instead of staying headless.