Kong/insomnia · error

MCP server url is required

Error message

MCP server url is required

What it means

Error "MCP server url is required" thrown in Kong/insomnia.

Source

Thrown at packages/insomnia/src/main/mcp/transport-streamable-http.ts:30

import type { Dispatcher } from 'undici';

import { type ConnectionContext, getFetchDispatcher, writeEventLogAndNotify, writeTimeline } from '~/main/mcp/common';
import { MCPAuthError, type McpOAuthClientProvider } from '~/main/mcp/oauth-client-provider';
import type { McpAuthEventWithoutBase, OpenMcpHTTPClientConnectionOptions } from '~/main/mcp/types';

// Extend undici RequestInit to include dispatcher, it's in node.js fetch but not in dom fetch.
interface NodeRequestInit extends RequestInit {
  dispatcher?: Dispatcher;
}

export const createStreamableHTTPTransport = async (
  context: ConnectionContext,
  options: OpenMcpHTTPClientConnectionOptions,
  authProvider: McpOAuthClientProvider,
) => {
  const { url, headers } = options;
  if (!url) {
    throw new Error('MCP server url is required');
  }

  const reduceArrayToLowerCaseKeyedDictionary = (acc: Record<string, string>, { name, value }: RequestHeader) => ({
    ...acc,
    [name.toLowerCase() || '']: value || '',
  });
  const lowerCasedEnabledHeaders = headers
    .filter(({ name, disabled }) => Boolean(name) && !disabled)
    .reduce(reduceArrayToLowerCaseKeyedDictionary, {});

  const mcpServerUrl = new URL(url);
  const transport = new StreamableHTTPClientTransport(mcpServerUrl, {
    requestInit: {
      headers: lowerCasedEnabledHeaders,
    },
    fetch: (url, init) => wrappedFetch(url, init || {}, context, authProvider),
    reconnectionOptions: {
      maxReconnectionDelay: 30_000,

View on GitHub (pinned to d9bb2b0142)

When it happens

Trigger: Thrown at packages/insomnia/src/main/mcp/transport-streamable-http.ts:30 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Kong/insomnia@d9bb2b0142 (2026-08-26). Data as JSON: /api/errors/b510e3f6fc4c64e9. Report an issue: GitHub.