Windows sandbox runner fails with CreateProcessAsUserW failed: 5 on Windows 11

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

26.602.4764.0

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.8524 x64

What issue are you seeing?

Codex Desktop is unable to execute any command inside the Windows sandbox.

All commands fail before execution with:

windows sandbox: runner error: CreateProcessAsUserW failed: 5

The command itself never starts.

The same commands execute successfully outside the sandbox via escalation.

Examples:

git status
Get-Location
dir

Additional log messages observed:

computer-use native pipe startup failed
Windows Computer Use helper paths are unavailable

Earlier logs also contained:

EBUSY: resource busy or locked

After clearing plugin caches and allowing bundled plugins to reinstall, the issue persists.

What steps can reproduce the bug?

1. Open Codex Desktop on Windows 11.
2. Use a configuration with:

[windows]
sandbox = "elevated"

1. Open a trusted project.
2. Ask Codex to execute a simple command in sandbox mode:

git status

or

Get-Location

or

dir

1. The command fails immediately.

Observed result:

windows sandbox: runner error: CreateProcessAsUserW failed: 5

The process is never created and the command never starts executing.

Environment:

• Codex Desktop: 26.602.4764.0
• codex-cli: 0.137.0-alpha.4
• Windows 11 Pro Insider Preview 26200.8524
• Sandbox mode: elevated

Diagnostics already performed:

• Windows Sandbox launches successfully.
• Containers-DisposableClientVM feature is enabled.
• vmcompute and hns services are running.
• hypervisorlaunchtype is set to Auto.
• CodexSandboxOffline and CodexSandboxOnline users exist and are enabled.
• Bundled helper binaries are present.
• Computer Use plugin is installed.
• Plugin caches were removed and regenerated.
• Commands execute correctly outside the sandbox via escalation.

What is the expected behavior?

Commands should execute normally inside the Windows sandbox.

For example:

git status

should start successfully and return repository status instead of failing before process creation.

Additional information

Impact: sandbox execution is completely unusable.

Every command fails regardless of command content.

This appears to be a failure during sandbox process creation rather than a failure of the executed command itself.

I would like to know whether this is a known issue in Codex Desktop 26.602.x / codex-cli 0.137.0-alpha.4 on Windows, or whether additional Windows configuration is required for CreateProcessAsUserW to succeed.