For our GPT - signing in isn't prompted on the mobile apps (it works fine on Web)

Hey @tomking, that’s confusing, and you’re not the only one seeing web and mobile behave differently here.

Most likely, mobile isn’t surfacing the GPT Action OAuth sign-in challenge properly. For Actions, auth should be configured as OAuth in the GPT editor so ChatGPT shows the “Sign in to [domain]” flow. I wouldn’t rely on WWW-Authenticate alone to trigger login.

A few things to double-check:

• OAuth is configured in the GPT Action settings
• Both callback URLs are allowlisted:
• chat.openai.com/aip/{GPT_ID}/oauth/callback
• chatgpt.com/aip/{GPT_ID}/oauth/callback
• Token response includes the expected fields like access_token, token_type, and optionally refresh_token / expires_in

If all of that is set and mobile still only says “Stopped talking to api-url,” I’d treat it as a mobile client parity bug and open a support ticket with a repro.

-Mark G.