ResourcesTroubleshooting

MCP

Debugging and troubleshooting MCP server issues

Connected account not found error

This error occurs when MCP cannot find a valid connected account for authentication:

  • Specify an account: Provide either connected_account_id or user_id in your MCP configuration
  • Default behavior: Without specification, MCP uses user_id=default. If multiple connections exist with the same user_id, the most recent is used
  • Verification checklist:
    • Account status is ACTIVE (not deleted)
    • Account belongs to the same auth config used to create the MCP server

Learn more: MCP Developer Guide

Getting 404 errors

Verify your URL format matches one of these patterns:

  • https://mcp.composio.dev/composio/server/<UUID>/mcp
  • https://apollo-<randomID>-composio.vercel.app/v3/mcp/<UUID>
  • https://apollo.composio.dev/v3/mcp/<UUID>

Testing and debugging

If experiencing issues, test your MCP server with:

This helps identify whether the issue is with your MCP client or the server.

Reporting MCP issues

When reporting to support, provide:

  • Error message: Complete error details
  • MCP server URL: The exact URL you’re connecting to
  • Testing results: Whether issue reproduces in MCP Inspector/Postman or only in specific client
  • Connected account ID: If facing connection issues
  • Reproduction steps: Clear steps to reproduce the issue

Getting help