I'm unable to install-and-require-helmet please help

[miku86]

You can see a detailed reply here:

Information security with helmet.js

When you go into package-lock.json, you can see your actual helmet version: 3.23.3. The lessons asks for 3.21.3. This is because you use ^3.21.3 in your package.json. There is a cause for using ^. You can read about npm semantic versioning.