Zoho Projects MCP connector returns HTTP 500 on all API calls for Zoho CRM Plus accounts

Summary

The Zoho Projects MCP connector fails with HTTP 500 on every API call when the Zoho account uses Zoho CRM Plus instead of standalone Zoho Projects.

Environment

• Claude Code version: current (desktop app, Windows 10)
• MCP connector: Zoho Projects (b90a6793-d9a4-4a7a-aecf-c1a2f1ab7884)
• Account type: Zoho CRM Plus — portal URL: https://crmplus.zoho.com/<org>/index.do/cxapp/projects/<portal-slug>
• OS: Windows 10 Home 10.0.19045

Steps to Reproduce

1. Install and authenticate the Zoho Projects MCP connector in Claude Code
2. Account must use Zoho CRM Plus (not standalone Zoho Projects)
3. Invoke any tool from the connector, e.g. getAllPortals (requires no parameters)

Actual Behavior

Every tool call returns HTTP 500 immediately:

Tool call failed: 500

Affected calls tested:

• getAllPortals (no parameters)
• Retried multiple times across different sessions — error is consistent, not transient

Expected Behavior

getAllPortals should return the list of Zoho Projects portals associated with the authenticated account.

Root Cause Hypothesis

The connector likely targets the standalone Zoho Projects API (projectsapi.zoho.com) which is not the correct endpoint for CRM Plus accounts. Zoho CRM Plus hosts Projects under crmplus.zoho.com and may require a different API base URL or OAuth scopes.

Evidence

• Zoho CRM MCP connector (7c3f0d3b-d6af-4bcf-a410-9a139baaa7da) works correctly on the same account — getModules returns full module list (Leads, Contacts, Deals, etc.)
• Re-authenticating the Zoho Projects connector does not resolve the error
• The Zoho Projects portal is accessible and active in the browser when logged in
• mcp-needs-auth-cache.json does not flag Zoho Projects as needing re-auth after reconnection — token is accepted, but API calls fail

Workaround

None available. Users with CRM Plus accounts cannot use the Zoho Projects connector at all.