I want to report a Codex Desktop App startup issue on Windows.

Summary

The Microsoft Store version of ChatGPT/Codex can hang indefinitely on the startup/loading page when `C:\Users\\.codex\config.toml` contains an invalid TOML escape sequence in an MCP server Windows path.

In my case, reinstalling, repairing, and resetting the app did not fix the issue, because the broken user config file remained under the user profile.

What happened

Codex opened a normal app window, but stayed stuck on the loading/startup page and never entered the main UI.

The root cause was an MCP server config entry like this:

args = ["-NoLogo", "...", "-File", "F:\ChatGPT-projiect\deepseek-mcp-local\start-deepseek-mcp.ps1"]

In TOML double-quoted strings, `\d` is not a valid escape sequence. This caused the entire config parse to fail.

The log repeatedly showed:

failed to reload config: C:\Users\<user>\.codex\config.toml:150:77:
missing escaped value, expected `b`, `e`, `f`, `n`, `r`, `\`, `"`, `x`, `u`, `U`

Impact

After the config parse failed, multiple core functions appeared to be unavailable or blocked, including:

From the user perspective, the app simply looked frozen on startup, with no visible error message.

Workaround

Changing the Windows path to use forward slashes fixed the issue:

args = ["-NoLogo", "...", "-File", "F:/ChatGPT-projiect/deepseek-mcp-local/start-deepseek-mcp.ps1"]

Using TOML literal strings should also avoid this escape parsing problem:

args = ['-NoLogo', '...', '-File', 'F:\ChatGPT-projiect\deepseek-mcp-local\start-deepseek-mcp.ps1']

Suggested improvements

  1. Codex should not block the entire desktop app startup when `config.toml` has a parse error.

  2. It should enter a safe mode or fallback mode and skip the broken MCP section.

  3. The UI should show a clear error message with the config file path and line number.

  4. If Windows paths are written by the GUI, they should be automatically normalized to `/`, escaped as `\\`, or written as TOML literal strings.

  5. Startup should perform a config health check before waiting on dependent RPC handlers.

Environment

  • OS: Windows 10, Build 26100, x64

  • App: ChatGPT / Codex Desktop, Microsoft Store version

  • Package: OpenAI.Codex_2p2nqsd0c76g0

  • Version observed: 26.803.5235.0