MCP server errors from Node, npx or uvx: fixes

Quick checklist

1. 1. Node version too old
2. 2. “npx” or “uvx” not found
3. 3. Slow first start
4. 4. Keep the -y flag

1. Node version too old

Check with node --version. context-mode needs Node 22.5 or newer and failed to start under Node 20.19 in our protocol check; Draw.io MCP also needs Node 22+. Install a current Node and point command at its absolute path (for example /path/to/node22/bin/npx). That is how we made both pass.

2. “npx” or “uvx” not found

Apps started from a dock or menu may not see the PATH your terminal uses. Run which npx or which uvx in a terminal and use that absolute path as command. No uvx at all? Install uv from the official instructions.

3. Slow first start

The first npx -y or uvx run downloads the package, which can exceed an app's startup timeout. Run the command once in a terminal so it's cached, then restart the app. In Claude Code you can raise MCP_TIMEOUT (milliseconds).

4. Keep the -y flag

npx -y answers yes to npx's install prompt. Without it, npx can wait for input that an app never sends.

Sources

• Node.js: Download
• npm docs: npx
• uv docs: Installation
• Claude Code docs: Connect Claude Code to tools via MCP

Links checked 2026-10-14. Items marked “Our tests” come from our own harness runs, shown on each server page with the date.