MCP Auth Issue

[guy-the-tech-guy]

What happened?

After successfully logging in through the OAuth popup, Claude.ai fails to connect to the MCP server. The error shown is "Your account was authorized but the integration rejected the credentials."

What did you expect to happen?

After logging in, Claude.ai should connect to my MCP server and the tools should be available.

Steps to reproduce

Go to Claude.ai Settings → Integrations → Add custom connector
Enter a remote MCP server URL
Click Add — a login page appears
Enter username and password and click Sign In
Page redirects back to Claude.ai
Error appears: "There was an error connecting to the MCP server... McpAuthorizationError: Your account was authorized but the integration rejected the credentials"

Additional info:
Server logs confirm the OAuth token is successfully issued after login, but Claude's backend (python-httpx) then makes a follow-up request to the MCP server with no Authorization: Bearer header — so the server correctly rejects it with a 401. The token is never used. This appears to be a known issue also reported at github.com/modelcontextprotocol/modelcontextprotocol/issues/2157.

Area

MCP Connector (adding/managing servers)

MCP Server (if applicable)

No response

Error messages or logs

Additional context

No response

[ktmcburney]

I am getting the exact same issue

Custom connector OAuth flow completes fully but Claude never sends the authenticated request.

Server logs show the complete flow:

1. POST /mcp → 401 (correct)
2. Metadata discovery → 200
3. GET /authorize → login form shown → 200
4. User authenticates (email + password + 2FA)
5. Redirect back to https://claude.ai/api/mcp/auth_callback with auth code → 302
6. POST /token → tokens issued → 200

After step 6, Claude should send POST /mcp with Authorization: Bearer but it never does. Instead it shows "Authorization with the MCP server failed."

• Team account, custom connector (beta)
• Self-hosted OAuth (not third-party redirect)
• Reference: ofid_08071f8b20828400

[wileyc427]

Same, my logs show:

POST /api/mcp 401 26.060 ms
GET /.well-known/oauth-protected-resource/api/mcp 200 0.639 ms - 104
GET /.well-known/oauth-authorization-server 200 0.681 ms - 423
[oauth] register — redirect_uris: [ 'https://claude.ai/api/mcp/auth_callback' ] client_name: Claude
[oauth] registered client: {clientId}
POST /api/oauth/register 201 3.225 ms - 234
[oauth] authorize — client_id: {clientId} redirect_uri: https://claude.ai/api/mcp/auth_callback
[oauth] authorize — redirecting to: https://claude.ai/api/mcp/auth_callback?code={callbackCode}
GET /api/oauth/authorize?response_type=code&client_id={clientId}&redirect_uri=https%3A%2F%2Fclaude.ai%2Fapi%2Fmcp%2Fauth_callback&code_challenge={challenge}&code_challenge_method=S256&state={state}&scope=claudeai&resource={resourceUrl} 302 2.447 ms - 192
GET /.well-known/oauth-authorization-server 200 0.715 ms - 423
[oauth] token — grant_type: authorization_code client_id: {clientId}
[oauth] token — issued for client: {clientId}
POST /api/oauth/token 200 4.351 ms - 447

/api/oauth/token returns the token, but there is no request after, presenting the token.

I get this error in Claude Desktop
Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: "ofid_8dcef4d4be429359"

• Pro plan, individual user/account
• Self-hosted OAuth
• Reference: ofid_8dcef4d4be429359

[felipepaes1984]

Is anyone looking at those issues? So many similar errors reported for weeks.

[RajeevDubey1981]

any update of this issue ?

[charlesemarsh]

Also looking for an update.

Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: "ofid_8e7247e5129345f3"

Pro plan, individual user/account
Self-hosted OAuth (not third-party redirect)
Reference: ofid_8e7247e5129345f3

[crondinini-ant]

@guy-the-tech-guy — we don't have a reference ID for your original report. If you can retry and share the ofid_ from the error toast, we can trace exactly what happened on our side for your server.

Looked up the reference IDs from the folks who shared them, and each one turned out to be a different cause:

@ktmcburney (ofid_08071f8b20828400) — OAuth completed fine and we did send the authenticated POST to your server with the Bearer token. Your server (or something in front of it) returned HTTP 403 Forbidden. This usually means a firewall or bot-protection layer is blocking the request before it reaches your application, which is why your app logs don't show the Bearer request even though we sent it. Issue #49 has more on this pattern if you're behind Cloudflare or similar.

@wileyc427 (ofid_8dcef4d4be429359) — our logs show the OAuth flow was initiated (client registered, auth URL generated) but I'm not seeing the callback or token exchange events for this reference. That's from Mar 19 so it may have partially aged out. If you can retry and open a new issue with the fresh ofid_, we can trace it properly — adding reference IDs to an existing thread makes them hard to track since each one usually turns out to be a different cause.

@charlesemarsh (ofid_8e7247e5129345f3) — OAuth completed, token was stored, and we sent the authenticated POST. Your server returned HTTP 402 Payment Required, which looks like a billing or entitlement check on your server's side rejecting the authenticated user — not an auth failure on our end.

The common thread: in the cases we can trace, our backend does send the Authorization: Bearer header. When the request doesn't show up in your application logs, something upstream (reverse proxy, WAF, bot protection) is usually intercepting it before your app sees it.

@felipepaes1984 — these reports look like the same issue because our error message is the same generic "Authorization with the MCP server failed" regardless of whether the actual cause was a 403 firewall block, a 402 billing check, a DNS failure, or something else entirely. As the traces above show, they're actually different problems on different servers that happen to surface the same way. We need to do better at showing what actually went wrong so people can tell their issue apart from someone else's.

[crondinini-ant]

Since this became a catch all issue and the original issue did not include an ofid_, I will be closing this.
If any of you have issues, please open a new issue! Thank you for your understanding :)
As I mentioned above, auth issues look the same but it's often caused by different issues, so please open a new issue with your ofid_ - that'll help us debug.
Thanks!

[abdul-mangrio]

@crondinini-ant, i know this is closed, but I was able to connect with NetSuite connector using Claude , now I am getting this error and URL says token exchange failed

Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: "ofid_1306452df44af8f7"

@crondinini-ant that would be great, if you could help with the ofid?