Windows sandbox state file corrupted with NUL bytes, causing repeated ACL/permission failures

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

26.616.81150

What subscription do you have?

Plus

What platform is your computer?

Windows 10

What issue are you seeing?

Codex Desktop on Windows got stuck with repeated sandbox ACL / permission failures for normal workspace operations.

Symptoms:

• Repeated approvals / blocks for normal workspace operations
• Local image reads failed with Windows sandbox ACL errors
• Some files were reported as owned by CodexSandboxOffline
• %USERPROFILE%\.codex\.sandbox\deny_read_acl_state.json was filled with NUL bytes instead of valid JSON

What steps can reproduce the bug?

I do not have exact repro steps, but I believe it happened after cancelling/stopping prompts while Codex was doing image generation / local image inspection / file editing.

Manually adding deny_read_acl_state.json filled with null bytes could potentially reproduce the issue.

What is the expected behavior?

Cancelling a prompt should not leave persistent corrupted Windows sandbox state. If deny_read_acl_state.json is invalid, Codex should detect that and regenerate it automatically.

Additional information

_No response_