OAuth MCP server works in ChatGPT Developer Mode ("Create App") but fails in App Review form — what does "unsupported OAuth config type" really mean?

Hi all,

I’m hoping someone can help me understand an error I’m hitting, and why the behavior differs between two OAuth flows in ChatGPT.

The Problem

With the same MCP server URL, with the same OAuth configuration:

• Works perfectly when connected via chatgpt.com → Developer Mode → Create App. The server supports both pre-defined and DCR modes no problems!

• Fails in the App Review submission form at Step 2 (“MCP Server”) when clicking Scan Tools , with:

MCP details save failed: OAuth discovery returned unsupported OAuth config type

Interestingly, “Scan Tools” on the review form worked fine for me on 21 April 2026 with a test (unpublished) app. The failure started showing up recent, on 6 May 2026 (attempts around ~05:00 and ~10:00 GMT+0800) against the same server.

What I’m trying to understand

1. What does “OAuth discovery returned unsupported OAuth config type” actually mean? Which part of the OAuth discovery document is it reporting an error about?
2. Why would the App Review form’s OAuth discovery treat a server differently from Developer Mode’s “Create App” flow, if both are ostensibly doing MCP OAuth discovery against the same URL?
3. Is there a stricter OAuth metadata requirement on the review path (e.g. specific authorization_servers, PKCE, or dynamic client registration fields) that Developer Mode doesn’t enforce? I’m struggling to debug what’s going on ~

Reproduction

1. Create a new App Review draft, fill in details up to Step 2: MCP Server
2. MCP server URL: https://example.com/api/mcp
3. Auth mode: OAuth
4. Click Scan Tools → error dialog appears

Screenshot of the error dialog:

If anyone has shipped an OAuth-backed MCP server through App Review recently, I’d love to know what discovery-document shape worked for you — and whether the two flows are expected to diverge.

Thank you!!