Unable to connect ChatGPT App to MCP Server

ChatGPT Apps SDK
1

Hello,

I’m trying to connect a ChatGPT app to an MCP server, and I’ve been getting the same kind of error for some time now. I already tested the MCP server with both MCP Inspector and MCP Jam. Both clients work with my MCP server. They perform the OAuth authentication correctly, and list/call the MCP tools.

In ChatGPT, when I add the app, it also performs the OAuth flow. However, it never finishes setting up the app, and shows me an error saying that there’s something wrong with the connection.

When I inspect the network calls in the browser, I see the following request failing:

POST https://chatgpt.com/backend-api/aip/connectors/links/oauth/callback 424 (Failed Dependency)

{
    "detail": {
        "error_code": "MCP_ACTION_DISCOVERY_FAILED",
        "message": "Authentication succeeded, action discovery failed",
        "connector_id": "asdk_app_6a4d1850e8d081918351efc789fbb8de",
        "link_id": "link_6a4d186e3bf081919e1180c9eab7d663",
        "cause": {
            "status_code": 401,
            "detail": "Reauthentication required"
        }
    }
}

On the server side, when the access token issued to the user is also logged for debugging purposes. I already inspect its claims, and both iss and aud claim match up with the advertised oauth protected resource.

In the MCP logs, we don’t see any request from the ChatGPT app attempting to list the tools with the access token that was issued, as if it didn’t like the access token. This is strange, because the other MCP clients worked without any issues.

Do you have any clue as to why is this happening, or how can I get more detailed logs for this?

2

Hey adrianorc, welcome to the community!

That's definitely inconvenient. My best guess is that ChatGPT may require refresh token support, while some other MCP clients may not.

The ChatGPT MCP app docs mention that when OAuth is used, the OAuth/OIDC provider should issue refresh tokens. For OIDC, the standard approach is to advertise and request offline_access. If offline_access isn't advertised or refresh tokens aren't issued, ChatGPT may lose access and users may need to reauthenticate.

So even if MCP Inspector and MCP Jam work, they may only be testing the immediate OAuth access token flow. ChatGPT may be stricter because it needs to create a persistent app connection, store credentials, and refresh them later.

I'd check whether your metadata is exposed at:

/.well-known/openid-configuration

or

/.well-known/oauth-authorization-server

Then confirm it advertises something like:

"scopes_supported": ["openid", "profile", "offline_access", ...]

Also make sure the token response actually includes a refresh_token.

I hope this helps.

Avinash