Windows Codex app 26.602.4764.0: new conversations timeout after helper update; sandbox setup os error 740

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

OpenAI.Codex 26.602.4764.0 from Get-AppxPackage. About dialog currently difficult to access because conversations hang.

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?

Codex Windows app issue — conversations timeout / no response after helper update.

Environment

• Codex app version: OpenAI.Codex 26.602.4764.0
• Subscription: ChatGPT Plus
• Platform: Windows x64
• WSL: Ubuntu-24.04, WSL2
• WSL checks completed:

• bash exists and runs
• default shell is /bin/bash
• bubblewrap installed
• Main WSL repo path:

• \\wsl.localhost\Ubuntu-24.04\home\<user>\projects\homestock-ai
• Windows repo path also exists:

• C:\Users\<user>\Documents\ProMEP_AI

Issue

After a local Codex helper update, Codex UI opens and login succeeds, but conversations do not respond.

Symptoms:

• New projectless conversation times out / cannot send message.
• Existing project conversations also do not respond.
• Login succeeds.
• UI opens normally.
• Repair and Reset were attempted.
• Switching runCodexInWindowsSubsystemForLinux between true and false did not restore message sending.
• No new sandbox log is created after message attempts.

Key evidence

Latest local helper folder:

C:\Users\<user>\AppData\Local\OpenAI\Codex\bin\fb2111b91430cb17
LastWriteTime: 2026-06-06 18:51:47

Older helper folders exist:

34ab3e1324cc55b5  2026-06-04
5b9024f90663758b  2026-05-22
ada252862d154cdd  2026-05-22

Previous sandbox log references the new helper and shows:

codex-windows-sandbox-setup.exe failed to spawn with os error 740

os error 740 appears to indicate elevation required. After this, conversations hang silently and no new sandbox log is produced.

Current config tested

Tested both runtime states:

{
  "runCodexInWindowsSubsystemForLinux": true,
  "integratedTerminalShell": "wsl"
}

and:

{
  "runCodexInWindowsSubsystemForLinux": false,
  "integratedTerminalShell": "powershell"
}

Neither restored message sending.

Steps already tried

1. Verified WSL distro:

• Ubuntu-24.04
• WSL version 2
• default shell /bin/bash

1. Installed / verified:

• bash
• bubblewrap
• git
• curl
• ca-certificates

1. Tried Codex in WSL mode.
2. Tried Codex in Windows / PowerShell mode.
3. Tried projectless new conversation.
4. Tried existing project conversations.
5. Signed in again successfully.
6. Ran Codex Repair.
7. Ran Codex Reset.
8. Backed up .codex before further changes.

Expected behavior

A projectless new conversation should respond to:

Say OK only.

Actual behavior

The message times out / does not send successfully. No assistant response is produced. No new sandbox log is created.

Request

Please advise whether this is a known Windows Codex app / sandbox helper / message transport regression in version 26.602.4764.0, and whether there is a safe workaround that does not delete .codex sessions, auth, or history.

What steps can reproduce the bug?

1. Install / update Codex Windows app to version OpenAI.Codex 26.602.4764.0.
2. Open Codex and sign in successfully.
3. Start a new projectless conversation.
4. Send a simple message such as:

Say OK only.

1. The message times out / no assistant response is produced.
2. Try the same test inside an existing project conversation.
3. The project conversation also does not respond.
4. Check .codex\.sandbox: no new sandbox log is created after the message attempt.
5. Check previous sandbox log: it references the latest helper folder and shows codex-windows-sandbox-setup.exe failing with os error 740.

I also tried:

• Repairing the Windows app.
• Resetting the Windows app.
• Re-signing in.
• Switching runCodexInWindowsSubsystemForLinux between true and false.
• Testing both projectless and project conversations.

The issue still reproduces.

What is the expected behavior?

A new projectless conversation should send successfully and return a simple response.

For example, after sending:

Say OK only.

Codex should respond with:

OK

Existing project conversations should also start normally and produce a response. If sandbox setup fails, Codex should surface a clear error instead of silently timing out.

Additional information

I have not uploaded any auth files, tokens, .env files, or full .codex backup because they may contain sensitive data.

Relevant local evidence:

Codex app version:
OpenAI.Codex 26.602.4764.0

Latest helper folder:
C:\Users\<user>\AppData\Local\OpenAI\Codex\bin\fb2111b91430cb17
LastWriteTime: 2026-06-06 18:51:47

Older helper folders:
34ab3e1324cc55b5  2026-06-04
5b9024f90663758b  2026-05-22
ada252862d154cdd  2026-05-22

Previous sandbox log showed:

codex-windows-sandbox-setup.exe failed to spawn with os error 740

WSL was verified separately:

• Ubuntu-24.04
• WSL2
• /bin/bash exists and runs
• default shell is /bin/bash
• bubblewrap installed
• repo path exists under /home/<user>/projects/homestock-ai

The issue now occurs even for projectless conversations, so it does not appear to be limited to a WSL project path.