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

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.

Start by tracing how the Windows update deploys helpers into .codex.sandbox-bin and compare that with .codex\plugins.plugin-appserver. Reproduce the failure with Get-Location and inspect the related sandbox/runtime deployment state, including codex-code-mode-host.exe and codex-windows-sandbox-setup.exe. Done means a fresh update initializes the runtime and Get-Location succeeds without manual copying.