NetSuite MCP connection broken after Claude update

I was about to post about the same problem under the claude-ai-mcp repo but it appears they may have just fixed it - you may want to try now. I was able to connect successfully as of about 15 minutes ago, for the first time since update.

Here's the details for the issue we were experiencing anyway (no longer experiencing) in case it's not resolved.
NetSuite MCP OAuth succeeds but connection fails post June 19 UTC deployment (blank METHOD / 404 in execution log)
Standard Tools SuiteApp and standard Netsuite connector from browsing Marketplace, nothing custom

Reference ID

ofid_b520cd4172d024a2

Server URL

https://<account-id>.suitetalk.api.netsuite.com/services/mcp/v1/suiteapp/com.netsuite.mcpstandardtools

Error shown in Claude

Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: ofid_b520cd4172d024a2

What the NetSuite AI Connector (MCP) execution log shows pre and post break

| Period | HTTP Status | Status | METHOD column |
|---|---|---|---|
| Pre-break | 200 | FINISHED | initialize, tools/list, tools/call, prompts/list, resources/list |
| Post-break | 404 | FAILED | (blank) |

What the NetSuite Login Audit Trail shows

• Token is successfully issued to an Anthropic IP (160.79.104.0/21) — OAuth completes on NetSuite's side
• Indicates he failure is post-token

OAuth discovery (all passing)

GET /.well-known/oauth-protected-resource/services/mcp/v1/suiteapp/com.netsuite.mcpstandardtools → 200
GET /.well-known/oauth-authorization-server → 200
GET /.well-known/openid-configuration → 200

- `registration_endpoint` present ✅
- `code_challenge_methods_supported: ["S256"]` ✅
- MCP endpoint returns clean `401` (no `3xx` redirect) ✅


## What has been ruled out (netsuite-specific issues were also ruled out but won't go into this here as it seems it was a Claude issue)

| Check | Result |
|---|---|

| WAF / edge block | ✅ No — Anthropic IPs reach NetSuite and tokens are issued |
| Credential-dropping redirect | ✅ No, clean `401` on MCP endpoint |
| OAuth discovery | ✅ All endpoints return 200 with valid metadata |
| Reconnecting the connector | ✅ Tried — no change |

## ChatGPT works on the same endpoint

ChatGPT successfully connects to the identical NetSuite MCP server (`com.netsuite.mcpstandardtools`) without issue, using its own separate integration record (different redirect URI). 

Update: Disconnecting and fully reconnecting the NetSuite MCP (re-auth from scratch) resolved the issue. The new error after retry was 'Authorization with the MCP server failed' (ref: \ofid_3d75be60feccd58e\) — different from the original connection error. A full disconnect/reconnect fixed it.

Thank you for taking the time to report this.

Closing as resolved. Both the original reporter and the second commenter have confirmed the connection succeeds again after the server-side change rolled out, with a full disconnect and reconnect clearing any stale authorization state left over from the window when it was broken.

If the failure returns with a fresh reference ID after a clean reconnect, please open a new issue with that ID.

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.