Windows desktop: repeated exec_command startup failure at 'apply deny-read ACLs'

Summary

Repeated local command execution failures in the Codex desktop app on Windows prevent even read-only commands from starting. The failure occurs during sandbox/process setup, before the requested command executes. This blocks reading source documents and generating a requested Word deliverable.

Observed errors

Most attempts return:

exec_command failed: CreateProcess { message: "Rejected(\"Failed to create unified exec process: helper_unknown_error: apply deny-read ACLs\")" }

Another attempt returned (user path redacted):

Failed to create unified exec process: orchestrator_helper_report_read_failed: setup helper exited with status Some(1); failed to read setup_error.json: parse <USERPROFILE>\.codex\.sandbox\setup_error.json

Reproduction observed in the affected session

1. Use Codex desktop on Windows with PowerShell, sandbox_mode=workspace-write and managed/restricted filesystem permissions.
2. Ask the agent to read a local text file using exec_command (for example, Get-Content -LiteralPath targeting an installed SKILL.md).
3. Process creation fails with the error above, without command output.
4. Retry across subsequent conversation turns: the same failure recurs. Both sequential attempts and read-only calls batched with other independent reads have failed.

Expected behavior

Authorized read-only commands start successfully, or an actionable permission/setup error identifies the specific problem.

Environment and limits of evidence

• Windows desktop app; PowerShell shell.
• Workspace and user-profile paths contain Cyrillic characters; causality is unknown.
• The issue was reproduced multiple times in the same task across multiple turns.
• App version and Windows build could not be collected because command execution is unavailable.
• A restart was suggested, but there is no evidence that it was performed or resolved the issue.
• No configuration changes or sandbox bypasses were attempted.
• Exact root cause is unknown. Please investigate sandbox helper setup, deny-read ACL application, and setup_error.json reporting.

This report is submitted at the affected user's explicit request. Document contents, names, full local paths, and other personal data have been omitted.

Start by reproducing the failure in the Windows desktop app with PowerShell, workspace-write sandboxing, and managed filesystem permissions. Trace the sandbox helper setup around applying deny-read ACLs and reporting setup_error.json. Done means authorized read-only commands start successfully, or failures identify the specific permission or setup problem.