MCP-JSONRPC-32600 Invalid Request Troubleshooting Guide

Overview

MCP-JSONRPC-32600 indicates the JSON-RPC request sent is not a valid Request object [^1]. This is a protocol-level error that typically occurs when the request format doesn't conform to the specification.

Error Response Format

{
  "jsonrpc": "2.0",
  "id": null,
  "error": {
    "code": -32600,
    "message": "Invalid Request",
    "data": {
      "reason": "missing jsonrpc field"
    }
  }
}

Common Causes and Solutions

Cause 1: Missing jsonrpc Field

Solution: Ensure the request includes "jsonrpc": "2.0" field [^2].

Cause 2: Missing method Field

Solution: Ensure the request includes a valid method field.

Cause 3: id Field Format Error

Solution: The id field should be a string or number, preferably a string [^3].

Cause 4: Invalid JSON Format

Solution: Validate JSON syntax, check quotes and brackets.

Request Structure Validation

A valid JSON-RPC 2.0 request must include:

• jsonrpc: "2.0"
• method: string
• id: string or number (optional, for requests requiring response)

Reference Sources

[^1]: JSON-RPC 2.0 Specification - Official protocol specification defining -32600 error code
[^2]: MCP Error Codes - MCP error codes detailed guide
[^3]: Stack Overflow - Json RPC error 32600 - Community discussion suggesting string format for id