Windows update regression: local execution fails because codex-code-mode-host.exe is missing from .sandbox-bin

Open 💬 5 comments Opened Aug 26, 2026 by chadw1ckwu

💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

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

26.820.7780.0

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

After updating the Codex Windows desktop app to the latest version on the morning of August 26, 2026, the local execution environment stopped working.

Before the update, the same machine and the same project worked normally. Codex could read and modify local files, execute PowerShell commands, use Git, run npm build/tests, and start the local preview.

Immediately after the update, all local execution tools stopped working. The problem also occurs in a new blank Codex conversation, so it does not appear to be project-specific.

Even a simple read-only command such as:

Get-Location

fails to start.

The recurring error is that Codex cannot find:

C:\Users\<username>\.codex\.sandbox-bin\codex-code-mode-host.exe

I verified that:

.codex\.sandbox-bin exists;
codex.exe exists there;
codex-command-runner.exe exists there;
codex-code-mode-host.exe is missing from .sandbox-bin;
however, an OpenAI-signed copy of codex-code-mode-host.exe exists under:

.codex\plugins\.plugin-appserver\

The Authenticode signature of that executable is reported as Valid and signed by OpenAI OpCo, LLC.

Restarting Windows, restarting the Codex/ChatGPT desktop app, and using Windows Apps → Advanced Options → Repair did not resolve the issue.

As a result, Codex currently cannot use PowerShell, read local project files, use Git, run builds/tests, or start local previews.

What steps can reproduce the bug?

Feedback ID: 01a0392a-8326-7fe3-95e0-b21c722ffa70

What is the expected behavior?

After updating the Codex Windows desktop app, the local execution environment should initialize automatically and remain compatible with the installed Codex version.

A basic command such as:

Get-Location

should execute successfully without requiring any manual runtime repair.

Required sandbox/runtime helpers such as codex-code-mode-host.exe and related components should be correctly deployed to the location expected by Codex.

Existing projects, file access, Git operations, shell commands, build/test commands, and local previews should continue working normally after an app update.

Additional information

Diagnostics

The .sandbox-bin directory exists and contains files including:

codex.exe
codex-command-runner.exe
several versioned codex-command-runner-*.exe files

However, codex-code-mode-host.exe is missing.

A copy exists at:

.codex\plugins\.plugin-appserver\codex-code-mode-host.exe

I checked this file using Windows Authenticode:

Get-AuthenticodeSignature

Result:

Status: Valid
Signer: OpenAI OpCo, LLC

The file under .plugin-appserver was updated on August 26, 2026, which suggests that the app update downloaded the runtime component but may not have deployed it to .sandbox-bin.

Troubleshooting already attempted

Fully restarted Codex / ChatGPT Desktop
Restarted Windows
Used Windows Apps → Advanced Options → Repair
Tested from a new blank Codex conversation
Tested a read-only PowerShell command
Inspected .codex\.sandbox-bin
Inspected .codex\plugins\.plugin-appserver
Verified Authenticode signatures

None of these resolved the original issue.

Additional diagnostic experiment

For diagnostic purposes only, I temporarily copied the OpenAI-signed helper from .plugin-appserver to the missing .sandbox-bin location.

This allowed execution to progress further, but then exposed additional sandbox/runtime errors, including:

missing codex-windows-sandbox-setup.exe
Windows error 1058 during process creation
missing field stage

These temporary manual changes were reverted. The system is currently back in the original failing state where codex-code-mode-host.exe is missing from .sandbox-bin.

This suggests the issue may involve incomplete sandbox/runtime deployment or version inconsistency after the Windows app update.

The issue started immediately after the August 26, 2026 Codex update. It did not occur before that update.

View original on GitHub ↗

5 Comments

github-actions[bot] contributor · 2 days ago

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

#40700
#40791

Powered by Codex Action

andrewclancy550-dev · 2 days ago

I can reproduce the same regression on another Windows machine installed from the Microsoft Store.

Environment / build information:

Installation source: Microsoft Store
About Codex displays: Powered by Codex & OWL
About Codex version: 26.820.60940
Release date shown in the app: August 26, 2026
Windows x64

Observed behavior:

After this update, any task that requires local execution fails before the requested command/tool can run. This affects unrelated workflows, for example:

installing/configuring a normal Windows application;
reading/writing local files;
invoking local 3D-modeling tools and exporting STL/STEP/OpenSCAD files.

The recurring error reported by Codex is:

Cannot find C:\Users\<username>\.codex\.sandbox-bin\codex-code-mode-host.exe

The failure is not specific to one project or skill: different tasks that require local command execution fail at the same runtime-host stage. Codex can still reason/respond in the UI, but it cannot safely execute the local commands needed to complete those tasks.

No manual runtime files were copied or replaced on this machine, and no workaround has been applied. The affected installation has been left unchanged for diagnosis.

One potentially useful detail is that the About dialog shows 26.820.60940, whereas this issue was originally reported with 26.820.7780.0. This may indicate that multiple 26.820 Windows Store/Desktop build identifiers map to the same affected runtime deployment path, or that the UI release identifier differs from the MSIX package build.

I can provide additional sanitized diagnostics if maintainers need them.

MilkyWay008 · 1 day ago

That missing codex-code-mode-host.exe after the 26.820.7780.0 update is the installer shipping a half-deployed runtime, and the error 1058 you hit after copying the helper over backs that up, the sandbox host service never got registered properly. The clean fix is a full reinstall so .sandbox-bin gets redeployed: uninstall the app, delete the runtime dirs under %USERPROFILE%\.codex and the Codex cache under %LOCALAPPDATA%, then reinstall from the Store. Before that, worth checking sc query for the sandbox host service and the logs under %USERPROFILE%\.codex\logs to see which stage of the deployment failed. oh, btw, I keep a portable Hermes OTG on a USB stick as a spare agent for exactly these update-breaks-the-install moments, https://github.com/MilkyWay008/Hermes-OTG if you want a look.

btzzcold · 1 day ago

I’m seeing the same issue on a newer ChatGPT desktop/Codex build.

Publisher: OpenAI
Desktop version: 26.820.9563.0

C:\Users\Admin\.codex\.sandbox-bin\codex-code-mode-host.exe is missing, so local commands and browser-backed checks fail with:

failed to spawn code-mode host
C:\Users\Admin\.codex\.sandbox-bin\codex-code-mode-host.exe:
The system cannot find the file specified. (os error 2)

The .sandbox-bin folder exists, but the required host executable does not. Windows Apps Repair and a normal reinstall did not restore it persistently. Windows Security Protection History shows no quarantine event.

Codex in VS Code works normally on the same machine; only ChatGPT desktop’s Codex/local runtime is affected. I have not copied or manually replaced any runtime binaries.

This appears to reproduce the same desktop runtime deployment regression on version 26.820.9563.0.

zemeng5208 · 1 day ago

I maintain WinBridge Recovery: https://github.com/zemeng5208/winbridge-recovery

This report is a high-confidence match for the local Windows repair layer WinBridge is intended to diagnose: the required codex-code-mode-host.exe is present in one OpenAI-managed location (.codex\plugins\.plugin-appserver) but missing from the active .codex\.sandbox-bin runtime location after the 26.820 update. The follow-on codex-windows-sandbox-setup.exe / error 1058 / missing field stage behavior also points to a partially materialized or version-inconsistent local helper/runtime state rather than a project-level problem.

WinBridge can help inspect the user-side runtime/helper materialization state, compare expected vs active helper locations/versions, identify partial staging or stale runtime state, and check for Windows file-lock/path conditions that may have prevented a complete refresh. It does not modify WindowsApps, bypass package protection, or guarantee a repair.

One important limitation: if the current 26.820 Desktop build itself no longer deploys codex-code-mode-host.exe (or related sandbox helpers) into the location its own launcher expects, and a clean local state immediately reproduces the same missing-helper layout, that is an upstream packaging/deployment regression. In that case WinBridge can help confirm the local state mismatch, but the persistent fix needs to come from Codex upstream rather than from local recovery.