✗ windows sandbox failed: orchestrator_helper_launch_canceled: ShellExecuteExW failed to launch setup helper: 1223

On affected Windows setups, every apply_patch call fails with this error — the agent can read your code but can’t edit a single file. It surfaces as apply_patch verification failed: ... fs sandbox helper failed with status exit code: 1, first reported against Windows app build 26.616.3767.0 in #29072. Proxy users are hit hardest, for reasons covered below.

Symptoms

• Every patch attempt fails with this error; reads and shell commands may still work (#29072).
• A Windows dialog may appear: codex-windows-sandbox-setup.exe - The specified module could not be found, pointing at the exe inside C:\Program Files\WindowsApps\OpenAI.Codex_... (#28982).
• Reinstalling, repairing, and resetting workspace dependencies don’t clear it (#28982).

Cause

Win32 error 1223 is ERROR_CANCELLED — the launch was blocked or dismissed before it ran (Microsoft docs). OpenAI hasn’t posted a root cause, so what follows is community diagnosis from #29072. The experimental features.network_proxy feature writes proxy ports into .codex\.sandbox\setup_marker.json and breaks the elevated setup-helper launch — and with a proxy in .codex\.env, the ports get written back every time Codex runs an elevated shell command. Separately, the reporter showed the helper exe fails from the WindowsApps package path but runs fine when copied, byte-identical, to a normal directory.

Fix

Community-reported workarounds, in the order the thread converged on:

1. Open .codex\.sandbox\setup_marker.json and set "proxy_ports": []. Multiple users on #29072 confirm patching works again — until the ports get re-added.
2. Stop the re-poisoning in config.toml: [shell_environment_policy] with exclude = ["ALL_PROXY", "all_proxy", "HTTP_PROXY", "http_proxy", "HTTPS_PROXY", "https_proxy"]. Trade-off per the same thread: shell commands like curl stop seeing your proxy.
3. Or disable features.network_proxy outright and empty proxy_ports one last time — one user reports that combination stuck (#29072).
4. Set sandbox = "unelevated" under [windows] — confirmed by several users, with one report of a split-writable-root failure in workspace-write mode (#29072).
5. CLI users: roll back to 0.139.0 — one reporter found elevated-sandbox apply_patch broken in every release from 0.140.0 onward (#29072).

Affected versions

Per user reports on #29072 and #28982: Windows app builds 26.616.3309.0 through 26.623.5546.0, and CLI 0.140.0 onward with sandbox = "elevated". A fix was expected in 0.143.0, whose notes cover system-proxy routing and Windows sandbox credential fixes — but users report the error still reproduces on app builds shipped after it. Windows sandbox setup failures as a class go back further; see #10601 from February 2026. Both issues remain open with no maintainer reply as of July 15, 2026.

Facts on this page verified July 15, 2026.