Windows sandbox setup fails applying deny ACE to E: repository .agents directory.

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

26.908.70816

What subscription do you have?

Corporate

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

Environment:

• Codex version/binary: 12219cbfbcbddde7
• Command runner: 0.154.0-alpha.6.2
• OS: Windows
• Repository: local NTFS volume E:
• Working repository: E:\repos\trunk\server
• Failure is reproducible after restarting Codex
• C: checkout works; E: checkout fails

Reproduction:

1. Start a new Codex chat against E:\repos\trunk\server.
2. Ask Codex to read temp.txt.
3. Command execution triggers sandbox setup.
4. Sandbox setup fails before the command can complete.

Relevant log:
[2026-09-16T23:54:05.594901900+00:00] deny ACE failed on E:\repos\trunk\server.agents: SetNamedSecurityInfoW failed for E:\repos\trunk\server.agents: 5
[2026-09-16T23:54:05.601425+00:00] setup refresh: processed 3 write roots (read roots delegated); errors=[...]
[2026-09-16 16:54:05.612 codex.exe] setup refresh: exited with status ExitStatus(1)

Additional details:

• Visualization ACL grant succeeds.
• E: is NTFS, Fixed, Healthy.
• The folder owner is BUILTIN\Administrators.
• Administrators has Full Control.
• CodexSandboxUsers has Modify access on the repository.
• An elevated PowerShell session can successfully add an explicit Administrators Full Control ACE.
• The same deny-ACE failure continues after restarting Codex.
• The command log shows:
  C:\WINDOWS\system32\cmd.exe /c cmd /c type temp.txt

Expected:
Sandbox setup should configure the repository and allow the command runner to read temp.txt.

Actual:
Sandbox setup returns ERROR_ACCESS_DENIED (5) while applying the deny ACE to .agents.

What steps can reproduce the bug?

Open/Create a project pointing to a repo folder on my newly installed E drive using the desktop app. Ask it to read the contents of a temp.txt file that I placed in the root folder of the repo.

What is the expected behavior?

I expect that the file should be read. If I Open/Create a project pointing to a repo folder on my C Drive, it can read the file that I put there.

Additional information

I had the Codex app guide me through a series of steps to isolate the problem and have pasted its analysis into this issue.

2026 0913 codes sandbox logs.txt

Start with the Windows sandbox setup path that applies the deny ACE to the repository’s .agents directory, focusing on the SetNamedSecurityInfoW failure and ERROR_ACCESS_DENIED (5). Reproduce against the NTFS E: repository and compare with the working C: checkout, then verify that setup completes and the command runner can read temp.txt.