Custom MCP connector fails with authorization error on Claude.ai (works in Claude Code and ChatGPT)

[migas5000]

What happened?

I cannot add my custom MCP server as a connector on Claude.ai. Every attempt to connect fails with the following error:

"Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: ofid_30157946bfbae806"

MCP server URL: https://werpy.webteam.pt/api/mcp/werpy

The failure happens in:

• Claude.ai (web) → Settings → Connectors
• Claude Desktop app → Connectors / Integrations UI

The same MCP server works correctly in:

• Claude Code (CLI)
• Claude Code launched from inside the Claude Desktop app
• ChatGPT (OpenAI) as a custom connector

This indicates the MCP server, its OAuth flow, credentials, and permissions are valid, and that the issue is specific to the Connectors/Integrations flow on Claude.ai and Claude Desktop.

What did you expect to happen?

The MCP server should connect successfully from the Claude.ai Connectors UI and from the Claude Desktop Integrations UI, in the same way it already connects from Claude Code and from ChatGPT, allowing me to use its tools inside Claude.ai conversations.

Steps to reproduce

1. Open Claude.ai (web) or Claude Desktop.
2. Go to Settings → Connectors (or Integrations in the Desktop app).
3. Click "Add custom connector".
4. Enter the MCP server URL: https://werpy.webteam.pt/api/mcp/werpy
5. Complete the OAuth / authorization flow.
6. Observe the error: "Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: ofid_30157946bfbae806"

For comparison:

• Adding the same URL as a custom MCP server in Claude Code works on the first try.
• Adding the same URL as a custom connector in ChatGPT also works on the first try.

Area

MCP Connector (adding/managing servers)

MCP Server (if applicable)

No response

Error messages or logs

No errors are recorded on the MCP server side for the failed attempts from Claude.ai / Claude Desktop. The OAuth/authorization requests from Claude Code and ChatGPT are logged and complete successfully against the same endpoint, which suggests the failure occurs before a fully-formed authenticated request reaches my server.

If there is a specific request ID or correlation ID on Anthropic's side tied to ofid_30157946bfbae806, I'm happy to cross-check against my server logs.

Additional context

• Support reference returned by the UI: ofid_30157946bfbae806
• MCP server: custom, HTTPS, publicly reachable.
• Clients tested:
  • Claude Code (CLI) — works
  • Claude Code inside Claude Desktop — works
  • ChatGPT custom connector — works
  • Claude.ai web Connectors — fails
  • Claude Desktop Integrations UI — fails
• OS: macOS (Claude Desktop)
• Account: signed in with a webteam.pt email (note: this domain has previously been associated with SSO-related login issues on my account — support ticket #215473561391578 — in case it's related to how the Connectors flow handles auth.)

Happy to provide additional logs, run specific tests, or share a sanitized trace of the OAuth handshake if useful.

[localden]

Thanks for the report. We traced the request ID. OAuth completes but your server returns 403 on the authenticated verification request. Please confirm Claude's outbound IP addresses are allowed through any WAF or firewall in front of your server, and that your server accepts the bearer token claude.ai obtained.