Intermittent MCP OAuth discovery failure: "MCP server does not implement OAuth

ChatGPT Bugs
1

I’m experiencing an intermittent issue while connecting my custom MCP server to ChatGPT.

Expected behavior
ChatGPT successfully discovers the OAuth configuration and returns the OAuth metadata (authorization URL, token URL, registration URL, PKCE configuration, etc.), after which the OAuth flow completes successfully.

Actual behavior
Occasionally, the same request fails with:

{
  "detail": "MCP server https://mcp.birdeye.com/mcp does not implement OAuth"
}

Observations

  • The issue is intermittent. Retrying the exact same connection sometimes succeeds without any changes.
  • When the request succeeds, ChatGPT’s POST /backend-api/aip/connectors/mcp/oauth_config endpoint returns the expected OAuth configuration.
  • When it fails, the same endpoint returns the “does not implement OAuth” error.
  • Most importantly, during failed attempts, no HTTP request reaches our MCP server (including the MCP endpoint, OAuth discovery endpoints, or any OAuth endpoints). Our server access logs show no incoming requests at all.
  • The exact same MCP server and OAuth implementation (Dynamic Client Registration + PKCE) works consistently with Claude and other MCP clients.

This makes it appear that the failure is occurring within ChatGPT’s OAuth discovery or connector backend before any request is sent to the MCP server.

Has anyone else experienced this intermittent behavior, or can the OpenAI team confirm whether this could be related to OAuth discovery caching or the MCP connector infrastructure?

I’ve attached screenshot of failed response.

In case of failure, this api return 404 with response body: {“detail”:“MCP server [my mcp server url here] does not implement OAuth”}. In this case there no API call at my MCP server.

Screenshot 2026-07-09 at 12.11.26 PM
Screenshot 2026-07-09 at 12.11.26 PM1878×726 90.8 KB

2

I’m surprised no one has left what the issue is. Check your firewalls. It’s itermittent because some ips are getting through, and some aren’t.

3

Welcome to the Community, @Vinesh_Kumar, and thanks for sharing such a detailed report.

For custom MCP servers using OAuth, ChatGPT relies on the server’s OAuth discovery and configuration endpoints to determine the authorization flow.

You can find more details here: Developer mode and MCP apps in ChatGPT.

Since the issue is intermittent, and the failed attempts return “does not implement OAuth” without any request reaching your MCP server, this would be best reviewed by our Support team.

Please contact support@openai.com and include:

  • Your MCP server URL
  • A screenshot of the failure
  • Whether the same setup works with MCP Inspector, Claude, or another MCP client
  • A sanitized HAR file captured through the failure
  • The timestamp and timezone of a failed attempt
  • The response from /.well-known/oauth-protected-resource

Please remove any tokens, credentials, secrets, or other sensitive information before sharing the files.

These details should help the team narrow down where the OAuth discovery or connection flow is failing.

- Saif