Maxim

Windows 10: "Complete Windows setup" fails with codex-windows-sandbox-setup.exe

Summary

The Microsoft Store version of ChatGPT/Codex cannot complete the initial "Complete Windows setup" process.

After selecting either Yes or No, the application immediately fails with an error related to codex-windows-sandbox-setup.exe.

The application never finishes initialization and cannot be used.

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Environment

Operating System

• Windows 10 Pro
• Version 22H2
• Build 19045

ChatGPT Desktop

• Installed from Microsoft Store
• Package: OpenAI.Codex
• Version: 26.715.7063.0

Hyper-V is enabled and detected by Windows.

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Steps to reproduce

1. Install ChatGPT/Codex from Microsoft Store.
2. Launch the application.
3. The application displays Complete Windows setup.
4. Click Yes or No.
5. Initialization fails with an error mentioning:

codex-windows-sandbox-setup.exe

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Expected behavior

The setup should complete successfully and ChatGPT should launch normally.

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Actual behavior

The application cannot complete Windows setup and exits.

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Diagnostics already performed

Windows integrity

Verified:

• DISM
• SFC

No integrity problems found.

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Hyper-V

Verified that Hyper-V is present and enabled.

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Package installation

Verified that the Microsoft Store package is installed correctly.

Package:

OpenAI.Codex

Version:

26.715.7063.0

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Package contents

Verified that the package contains Codex.exe.

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Local runtime cache

Verified:

%LOCALAPPDATA%\OpenAI\Codex\bin

Contents:

codex.exe
codex-command-runner.exe
codex-code-mode-host.exe
codex-windows-sandbox-setup.exe
rg.exe

The helper executable is present.

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Sandbox helper

Launching

codex-windows-sandbox-setup.exe

manually works.

It exits with:

Error: helper_request_args_failed: expected payload argument

This indicates:

• Windows can execute the helper.
• The executable is functional.
• It expects arguments from the parent process.

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Digital signature

Verified using:

Get-AuthenticodeSignature

Result:

Status: Valid

Publisher:

OpenAI OpCo, LLC

Certificate chain is valid through Microsoft.

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LocalState

Verified that

%LOCALAPPDATA%\Packages\OpenAI.Codex_2p2nqsd0c76g0\LocalState

exists.

No useful application logs are created before failure.

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Reinstallation attempts

Performed multiple times:

• uninstall
• reinstall
• remove application data
• remove .codex
• reinstall from Microsoft Store

The issue persists.

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Windows Error Reporting

Windows records WER events during startup attempts.

Most recent report:

StoreAgentInstallFailure1

This appears related to Microsoft Store acquisition rather than the application crash.

No useful crash report for codex.exe or
codex-windows-sandbox-setup.exe
is generated.

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Conclusion

The issue does not appear to be caused by:

• missing executable
• damaged executable
• invalid signature
• broken installation
• missing runtime files
• disabled Hyper-V

The helper executable:

• exists,
• launches correctly,
• has a valid OpenAI signature,
• is trusted by Windows.

This suggests the failure occurs while the desktop application attempts to invoke the helper during the "Complete Windows setup" phase.

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Request

Could you please investigate whether this is a regression in:

OpenAI.Codex 26.715.7063.0

on

Windows 10 Pro 22H2 (Build 19045)

The issue occurs before the application produces useful logs, making local troubleshooting extremely difficult.