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Codex Issues / #40762

Windows: Codex fails to start after update - bundled codex.exe returns "Access is denied"

Resolved 💬 2 comments Opened Aug 26, 2026 by xiaodeng2025 Closed Aug 26, 2026
💡 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 app to version 26.820.7780.0 today, Codex can no longer start.

It immediately shows:

“ChatGPT failed to start.
Unable to locate the Codex CLI binary.”

Codex was working normally before the update.

I confirmed that the bundled codex.exe still exists in the application package, but running it directly in PowerShell returns “Access is denied”.

The bundled codex.exe is also marked with the Encrypted file attribute.

It appears that the CLI file exists, but Windows cannot execute it after the update.

<img width="350" height="125" alt="Image" src="https://github.com/user-attachments/assets/7d64bf9d-d220-472a-8598-64ec0e520ddf" />
<img width="687" height="203" alt="Image" src="https://github.com/user-attachments/assets/ee4f72ae-bfc0-4d5f-9f12-503039210b2a" />

What steps can reproduce the bug?

  1. Use a working Codex Windows desktop installation.
  1. Update Codex to version 26.820.7780.0.
  1. Launch Codex.
  1. Codex immediately fails with:

“Unable to locate the Codex CLI binary.”

  1. Run the bundled CLI manually in PowerShell:

$pkg = (Get-AppxPackage OpenAI.Codex).InstallLocation
& "$pkg\app\resources\codex.exe" --version

  1. PowerShell returns “Access is denied”.

The issue occurs every time Codex is launched after the update.

What is the expected behavior?

_No response_

Additional information

  1. Use a working Codex Windows desktop installation.
  1. Update Codex to version 26.820.7780.0.
  1. Launch Codex.
  1. Codex immediately fails with:

“Unable to locate the Codex CLI binary.”

  1. Run the bundled CLI manually in PowerShell:

$pkg = (Get-AppxPackage OpenAI.Codex).InstallLocation
& "$pkg\app\resources\codex.exe" --version

  1. PowerShell returns “Access is denied”.

The issue occurs every time Codex is launched after the update.

View original on GitHub ↗

2 Comments

github-actions[bot] contributor · 2 days ago

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

  • #40700
  • #40752

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xiaodeng2025 · 2 days ago

Confirmed: this appears to be a duplicate of #40700.

I am seeing the same issue on Codex App 26.820.7780.0 / Windows 10.0.26200.0 x64. The bundled codex.exe exists, is marked Encrypted, and fails to execute with "Access is denied" immediately after the update.