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MCP client error

spawn npx ENOENT

An MCP client prints this when a stdio server's command is npx and the operating system cannot find it to start it.

The client could not start npx.
The server never launched.

Get the app other errors

What it means

ENOENT means "no such file". On Windows, npx is a batch shim, npx.cmd. Node's spawn finds .cmd files through PATHEXT only when the call runs through a shell, so a bare npx command fails (Claude Code issue 58510).

On macOS and Linux the same error means npx is not on the PATH the client runs with. A client started from a launcher can have a shorter PATH than your terminal.

Fix it

  1. On Windows, run it through cmd. Set the server's command to cmd and put /c and npx first in args: 
    {
  "command": "cmd",
  "args": ["/c", "npx", "-y", "@upstash/context7-mcp"]
}

    The reporter on issue 58510 verified this on six plugins. A change made inside ~/.claude/plugins/cache is lost when the plugin updates, so keep the server in your own config. On Windows, claude mcp add can rewrite /c into C:/ (issue 46360), so edit the JSON file instead.

  2. Elsewhere, find npx with which npx and put the full path in command, for example /usr/local/bin/npx.
  3. Check that Node is installed with node -v. npx comes with it.

With superbot

This is a local start-up error, and superbot does not fix it. A remote MCP server connected by URL is an alternative: it starts no local process, so there is no npx to find.

superbot is one. Connect it from Claude Code with:

claude mcp add --transport http superbot https://api.superbot.gg/mcp -s user

Then run /mcp in a new session and sign in. The one tool, named superbot, reads pages and searches the web.

With no browser, post to the install route instead.

curl -fsS -X POST https://api.superbot.gg/mcp/install -d client=claude-code

This needs an account.
An agent with none signs you in through /auth.md.
You read back one emailed code.

Source: anthropics/claude-code issue 58510 and firecrawl/firecrawl-mcp-server issue 38. Issue 46360 covers the /c rewrite. Read on 2026-10-18.