Codex Desktop 26.830.60940 — all models return 404 after upgrade on macOS

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

26.830.60940

What subscription do you have?

Codex 20x

What platform is your computer?

macOS, Apple Silicon

What issue are you seeing?

Immediately after upgrading Codex Desktop to version 26.830.60940, Codex stopped working completely.

All models fail, including newly created threads.

Error:

unexpected status 404 Not Found: Unknown error,
url: https://chatgpt.com/backend-api/codex/responses,
cf-ray: a3558bc9fffc613f-BOM

The problem started immediately after the application upgrade.

What steps can reproduce the bug?

Upgrade Codex Desktop to 26.830.60940.
Open an existing workspace or repository.
Start a brand-new Codex thread.
Select any available model.
Send any prompt.
Request fails with HTTP 404.

What is the expected behavior?

Expected behavior:
Codex should send the request and return a response normally.

Actual behavior:
Every model and every new conversation immediately fails against:

https://chatgpt.com/backend-api/codex/responses

Additional information

Additional information:

Existing conversations fail.
Brand-new conversations also fail.
Switching models does not help.
Restarting Codex does not help.
The issue began immediately after upgrading to 26.830.60940.
Codex CLI is not installed separately on this Mac, so I cannot currently test whether the CLI is affected.
Cloudflare edge shown in the error is BOM.

Reproduce the failure on macOS Apple Silicon by upgrading to Codex Desktop 26.830.60940, then start both existing and new threads with different models. Inspect the request to https://chatgpt.com/backend-api/codex/responses; done means requests succeed and return responses for all tested models and conversation types.