Codex CLI: 0.151.0, installed from the official @openai/codex npm package.

[nattapong18-en]

OS: CachyOS Linux x86_64
Codex CLI: 0.151.0, installed from the official @openai/codex npm package.

Exact error:

Token exchange error: error sending request for url (https://auth.openai.com/oauth/token)
Error logging in: Token exchange failed: error sending request for url (https://auth.openai.com/oauth/token)

I have already tested codex login --device-auth; it fails as well.

This is not a corporate network. There is no proxy, VPN, or SSL inspection. HTTP_PROXY, HTTPS_PROXY, ALL_PROXY, CODEX_CA_CERTIFICATE, and related environment variables are unset. I have also tested a different network/mobile hotspot, disabled IPv6, reinstalled Codex, tried multiple CLI versions, and used a clean ~/.codex directory.

The system clock is synchronized by NTP. Browser authorization succeeds and the callback reaches localhost:1455, so the loopback redirect is working.

Direct connectivity to the exact token endpoint also works:

POST https://auth.openai.com/oauth/token returns HTTP/2 400 with an expected invalid grant_type=test response, through Cloudflare BKK. This confirms DNS, TCP, TLS, HTTP/2, and the OpenAI token endpoint are reachable from this machine.

The mcp_oauth_callback_port settings apply to MCP-server OAuth, not the Codex account login flow, and the localhost callback has already succeeded.

This matches openai/codex issue #41434. The automated troubleshooting has been exhausted. Please create a support ticket and escalate this to a human technical agent as a Codex CLI OAuth/token-exchange defect. This is a personal paid ChatGPT Plus account and there is no workspace administrator.