codex - 💡(How to fix) Fix Windows Codex app: Browser/node_repl bridge fails with sandbox elevation error

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

codex 26.519.81530

What subscription do you have?

codex plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

Codex Windows app 26.519.81530 Browser / node_repl bridge fails before browser opens. mcp__node_repl__.js returns: windows sandbox failed: spawn setup refresh

Sandbox log shows: setup refresh failed to spawn codex-windows-sandbox-setup.exe: The requested operation requires elevation. (os error 740)

Manual node_repl.exe --disable-sandbox diagnostic can run JS successfully, but Codex regenerates .codex/config.toml with args = [] on restart.

What steps can reproduce the bug?

1. Open Codex Windows app.
2. Start a chat and ask Codex to perform any task that requires the Browser plugin, for example: "test the browser" or "open example.com in the browser".
3. Codex attempts to use mcp__node_repl__.js to initialize the browser runtime.
4. The bridge fails before any browser page opens.

I also reproduced the lower-level bridge issue by calling mcp__node_repl__.js with a trivial script, not involving any website:

nodeRepl.write(JSON.stringify({ ok: true }, null, 2));

That also fails with the same sandbox error.

What is the expected behavior?

The Browser plugin should initialize successfully, open or connect to the in-app browser, and allow Codex to inspect pages such as https://example.com.

actual behavior: The browser never opens/connects. mcp__node_repl__.js exits immediately with:

node_repl kernel exited unexpectedly windows sandbox failed: spawn setup refresh reason: stdout_eof

The sandbox log shows the underlying Windows error:

setup refresh: failed to spawn codex-windows-sandbox-setup.exe: The requested operation requires elevation. (os error 740)

Additional information

A manual diagnostic using node_repl.exe --disable-sandbox can run JavaScript successfully, so the issue appears specific to the sandbox setup path. However, Codex regenerates .codex/config.toml with args = [] on restart, so the workaround cannot be persisted from user config.

Additional data point: installed Chrome headless works on the same machine. A separate smoke check using local Chrome loaded an HTML page, rendered the title, ran JavaScript, and exited cleanly. So this does not appear to be a general Chrome/browser rendering problem.

The failure appears specific to the Codex in-app browser backend / node_repl bridge startup path.