Windows: Agent sandbox setup succeeds but .sandbox-bin remains empty
What version of the IDE extension are you using?
v26.616.81150
What subscription do you have?
ChatGPT Go
Which IDE are you using?
VS Code
What platform is your computer?
Microsoft Windows NT 10.0.26200.0 x64
What issue are you seeing?
The VS Code extension repeatedly asks me to set up the Agent Sandbox.
The sandbox setup appears to complete successfully, but the runtime is never installed because .sandbox-bin remains empty.
As a result, every time I restart VS Code I am asked to set up the Agent Sandbox again.
What steps can reproduce the bug?
- Install the Codex VS Code extension.
- Click Set up Agent Sandbox.
- Run the initial setup with Administrator permissions.
- Close VS Code.
- Start VS Code normally.
What is the expected behavior?
After completing the Agent Sandbox setup, the runtime should be installed and the extension should work normally.****
Additional information
Environment:
- Microsoft Windows NT 10.0.26200.0 x64
- VS Code 1.126.0 (User Setup)
- Codex extension version: v26.616.81150
- ChatGPT Go
- WSL not installed
- Avast Antivirus (also tested with Avast completely disabled)
Actual behavior:
The sandbox setup appears to complete successfully.
The sandbox log reports successful setup (firewall rules, ACLs, setup binary completed).
However, %USERPROFILE%\.codex\.sandbox-bin is created but remains completely empty.
The following files are never created:
- codex.exe
- codex-command-runner-0.142.0.exe
Because of this, every time VS Code starts the extension asks me to set up the Agent Sandbox again.
Comparison with another machine:
I compared my machine with another Windows 11 machine using:
- the same Codex extension version
- the same VS Code version
- WSL not installed
On the working machine:
%USERPROFILE%\.codex\.sandbox-bin
contains:
- codex.exe
- codex-command-runner-0.142.0.exe
On my machine, the directory is created but remains completely empty after the sandbox setup reports success.
Troubleshooting already performed:
- Reinstalled VS Code
- Reinstalled the Codex extension
- Deleted the entire %USERPROFILE%\.codex directory
- Recreated the sandbox
- Ran the initial setup as Administrator
- Started VS Code normally afterwards
- Compared NTFS permissions with the working machine
- Compared the CodexSandboxUsers group with the working machine
- Compared the .codex directory structure with the working machine
- Disabled Avast Antivirus during installation
- Verified LongPathsEnabled = 1
- Confirmed that codex.exe is not present anywhere under %USERPROFILE%\.codex
- Confirmed that no codex.exe is present in %LOCALAPPDATA%\Temp
None of these steps changed the behavior.
Additional information:
The sandbox setup log finishes successfully and contains no errors.
It ends with entries similar to:
- setup binary completed
- read ACL run completed
There is no indication that the runtime (codex.exe) is ever downloaded or installed.
<img width="1095" height="367" alt="Image" src="https://github.com/user-attachments/assets/2c10c42b-0064-45fb-831d-3e70b0fe1292" />