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Windows Codex App: sandbox setup fails globally in clean C:\temp workspace #26737

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Windows Codex App: sandbox setup fails globally in clean C:\temp workspace#26737
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appIssues related to the Codex desktop appbugSomething isn't workingsandboxIssues related to permissions or sandboxingwindows-osIssues related to Codex on Windows systems

Description

@dfaverill
dfaverill
opened on Jun 6, 2026

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

26.601.10930

What subscription do you have?

ChatGPT Pro

What platform is your computer?

Windows 11, x64

What issue are you seeing?

The Codex Windows app cannot set up its sandbox. The issue appears global, not workspace-specific.

Exact error shown in the Codex app:

Couldn't set up non-admin sandbox
Retry setup to continue

Earlier I also saw:

Couldn't set up Agent sandbox with Admin permissions
You can continue with the non-admin sandbox

I tested this in two different workspaces:

  1. Main workspace:
    D:\Download\download\GPT Ethiopia Podcast\AS

  2. Clean test workspace:
    C:\temp\codex_test_clean

The clean test workspace was newly created and empty. The same sandbox setup error still occurred there.

Troubleshooting already attempted:

  • Fully closed Codex from Task Manager.
  • Relaunched Codex as administrator.
  • Tried Retry setup multiple times.
  • Changed permission mode away from Full access to Ask for approval.
  • Opened Codex settings → Configuration.
  • Ran Diagnose issues in Codex Workspace.
  • Diagnose result: Codex dependencies look healthy.
  • Renamed the main workspace .codex folder to:
    .codex_broken_20260605
  • Added this config:
    [windows]
    sandbox = "elevated"
  • Restarted Codex and tested again.
  • Then changed it to:
    [windows]
    sandbox = "unelevated"
  • Restarted Codex and tested again.
  • Opened a clean workspace at:
    C:\temp\codex_test_clean
  • Retry setup still failed in the clean workspace.

Expected behavior:

Codex should initialize the Windows sandbox and allow a task to start.

Actual behavior:

Codex repeatedly fails before any task can run. Since the same error happens in a brand-new clean C:\temp workspace, this seems to be a global Windows sandbox setup failure rather than corruption in my original project folder.

What steps can reproduce the bug?

  1. Install/open Codex Desktop on Windows 11.
  2. Open a workspace.
  3. Try to start any task.
  4. Codex shows: Couldn't set up non-admin sandbox.
  5. Click Retry setup.
  6. The same sandbox setup error returns.
  7. Close Codex completely using Task Manager.
  8. Relaunch Codex as administrator.
  9. Try setup again.
  10. Codex still fails.
  11. Create a brand-new clean folder: C:\temp\codex_test_clean.
  12. Open that clean folder as a new Codex workspace.
  13. Try Retry setup again.
  14. The same non-admin sandbox setup failure occurs in the clean workspace.

What is the expected behavior?

Codex should successfully initialize the Windows sandbox in a normal local workspace, including a clean folder such as C:\temp\codex_test_clean, and then allow a task to start.

Additional information

Additional notes:

  • The issue happens before any Codex task can run.
  • The Codex settings diagnostic says: Codex dependencies look healthy.
  • The failure persists after restarting Codex and relaunching as administrator.
  • The failure persists after testing both windows.sandbox = "elevated" and windows.sandbox = "unelevated".
  • The failure also persists in a new clean local folder, so it does not appear to be caused only by my original project workspace.
  • Screenshots are available showing the repeated sandbox setup failure.

Activity

  1. dfaverill
    added
    appIssues related to the Codex desktop app
    on Jun 6, 2026
  2. github-actions
    added
    bugSomething isn't working
    windows-osIssues related to Codex on Windows systems
    sandboxIssues related to permissions or sandboxing
    on Jun 6, 2026

  3. github-actions commented on Jun 6, 2026

    @github-actions
    github-actionsBot
    on Jun 6, 2026 – with GitHub Actions
    Contributor

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

    Powered by Codex Action

  4. dfaverill commented on Jun 6, 2026

    @dfaverill
    dfaverill
    on Jun 6, 2026 via email
    Author

  6. ax-openai commented on Jun 12, 2026

    @ax-openai
    ax-openai
    on Jun 12, 2026 – with ChatGPT Codex Connector

    Closing as resolved.

  7. ax-openai
    closed this as completedon Jun 12, 2026

  8. tavitsme commented on Jun 18, 2026

    @tavitsme
    tavitsme
    on Jun 18, 2026 – with ChatGPT Codex Connector

    Adding another resolved Windows case with the same sandbox setup symptom, in case it helps future diagnostics or users who find this issue.

    Symptoms

    Codex Desktop App on Windows could not start chats or load plugins. The app showed sandbox setup failures including:

    • Couldn't set up Agent sandbox with Admin permissions
    • Couldn't set up non-admin sandbox

    Root cause in this case

    The Windows virtualization/sandbox prerequisites were not enabled or installed:

    • Hyper-V was disabled
    • Windows Sandbox / Containers-DisposableClientVM was disabled
    • Virtual Machine Platform was disabled
    • WSL2 was not installed
    • No Linux distro was installed

    Fix applied

    Enabled the required Windows features from an Administrator PowerShell session:

    • Microsoft-Hyper-V-All
    • Containers-DisposableClientVM
    • VirtualMachinePlatform
    • Microsoft-Windows-Subsystem-Linux

    Then installed Ubuntu:

    wsl --install -d Ubuntu

    After rebooting Windows, created/updated %USERPROFILE%\.codex\config.toml with:

    [windows]
sandbox = "unelevated"
sandbox_private_desktop = false

    Then fully quit and reopened Codex Desktop App. After that, chats started normally and plugins loaded again.

    System

    • Windows 11 Pro
    • Build 26200
    • VirtualizationBasedSecurity = 2 / VBS enabled

    This was a separate user machine from the earlier comments. The main takeaway is that the app's generic sandbox setup errors may also be caused by missing Windows optional features / WSL2 setup, not only Codex config corruption or elevated ACL setup failure.

  9. tavitsme commented on Jun 18, 2026

    @tavitsme
    tavitsme
    on Jun 18, 2026 – with ChatGPT Codex Connector

    One additional note from the affected user: this took about an hour of assisted debugging and consumed paid Codex/ChatGPT usage before the actual prerequisite issue was identified.

    The app surfaced only generic sandbox setup errors:

    • Couldn't set up Agent sandbox with Admin permissions
    • Couldn't set up non-admin sandbox

    In this case, the actionable fix was to enable/install the missing Windows prerequisites: Hyper-V, Windows Sandbox / Containers-DisposableClientVM, Virtual Machine Platform, WSL2, and an Ubuntu distro, then restart and use the unelevated sandbox config.

    It would be helpful if the app's setup diagnostics could explicitly detect and report missing Windows features/WSL prerequisites before users spend paid usage debugging a generic sandbox failure. If there is an appropriate support/credit path for users who spent significant paid usage on this unclear setup failure, please consider this case as well.

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