Cursor 3.3.0 RevenueCat MCP Authentication Error

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I was trying to use RevenueCat MCP as described in RevenueCat MCP Server Setup | In-App Subscriptions Made Easy – RevenueCat
But the authentication process couldn’t be completed successfully.

Here is my mcp.json

{
  "mcpServers": {
    "stitch": {
      "url": "https://stitch.googleapis.com/mcp",
      "headers": {
        "X-Goog-Api-Key": "token"
      }
    },
    "gemini": {
      "command": "npx",
      "args": ["@houtini/gemini-mcp"],
      "env": {
        "GEMINI_API_KEY": "token"
      }
    },
    "revenuecat": {
      "url": "https://mcp.revenuecat.ai/mcp",
      "headers": {
        "Authorization": "token"
      }
    }
  }
}

But after tapping Connect button at Cursor Settings screen and Authorizing at RevenueCat’s website Cursor show Error-Show Output message at listing. And here is the output.

2026-05-12 15:01:52.446 [info] [V2] Handling DeleteClient action, reason: server_disabled
2026-05-12 15:01:53.145 [info] [V2] Handling CreateClient action
2026-05-12 15:01:53.145 [info] [V2 FSM] connection:connect_start: conn=idle,auth=unknown -> conn=connecting,auth=unknown
2026-05-12 15:01:53.603 [info] MCP OAuth provider initialized
2026-05-12 15:01:53.609 [info] tokens() returning OAuth tokens
2026-05-12 15:01:53.690 [warning] MCP HTTP exchange completed
2026-05-12 15:01:53.763 [warning] MCP HTTP exchange completed
2026-05-12 15:01:53.833 [warning] MCP HTTP exchange completed
2026-05-12 15:01:53.909 [info] MCP HTTP exchange completed
2026-05-12 15:01:53.944 [info] Using redirect URL
2026-05-12 15:01:53.944 [info] Returning stored OAuth client_id
2026-05-12 15:01:53.944 [info] Using redirect URL
2026-05-12 15:01:53.950 [info] tokens() returning OAuth tokens
2026-05-12 15:01:54.267 [info] MCP HTTP exchange completed
2026-05-12 15:01:54.269 [info] MCP OAuth tokens persisted
2026-05-12 15:01:54.291 [info] OAuth tokens saved
2026-05-12 15:01:54.293 [info] tokens() returning OAuth tokens
2026-05-12 15:01:54.364 [warning] MCP HTTP exchange completed
2026-05-12 15:01:54.367 [error] OAuth fallback failed after MCP server returned 401 for configured Authorization header; surfacing original 401 Streamable HTTP error: Server returned 401 after successful authentication
2026-05-12 15:01:54.368 [warning] Connection failed: HTTP 401 Unauthorized from MCP server while using configured Authorization header
2026-05-12 15:01:54.368 [warning] [V2 FSM] connection:connect_failure: conn=connecting,auth=unknown -> conn=failed,auth=unknown
2026-05-12 15:01:54.369 [info] CreateClient completed, connected: false, statusType: error

Steps to Reproduce

Add RevenueCat MCP, try to connect and authorize

Operating System

MacOS

Version Information

Version: 3.3.30 (Universal)
VSCode Version: 1.105.1
Commit: 3dc559280adc5f931ade8e25c7b85393842acf30
Date: 2026-05-09T18:28:42.332Z
Layout: editor
Build Type: Stable
Release Track: Default
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Darwin arm64 25.4.0

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

Hey, this isn’t a bug. The RevenueCat config is wrong. RevenueCat MCP uses OAuth, and when you add a static Authorization: "token" header, it gets sent alongside the OAuth token and breaks the request. The logs show the OAuth flow succeeds (OAuth tokens saved), but the next request still goes out with the static header and the server returns 401.

Remove the headers block for RevenueCat. OAuth will handle it:

"revenuecat": {
  "url": "https://mcp.revenuecat.ai/mcp"
}

Then click Connect and complete the auth flow on the RevenueCat site. It should connect. Let me know if you still run into issues.

6

In that case RevenueCat’s documents are wrong. Actually linter warns about header attribute but I disregarded because of documents.

Anyway thanks for the information, I will try and close this topic if it works.