Scoped Package 404 (Missing Registry Mapping) in CI - Fix Scope Resolution

A 404 for a scoped package usually means npm queried the wrong registry. Without a scope-to-registry mapping, npm asks the public registry for a private scope and gets nothing.

What this error means

npm install returns 404 Not Found for an @scope/package even though it exists in your private registry, because .npmrc has no mapping telling npm where that scope lives.

npm

npm ERR! code E404
npm ERR! 404 Not Found - GET https://registry.npmjs.org/@acme%2fcore
npm ERR! 404 '@acme/core@^1.0.0' is not in the npm registry.

Common causes

No scope-to-registry mapping in .npmrc

The scope is not mapped to its private registry, so npm defaults to the public one, which does not host it.

The mapping exists locally but not in CI

A developer .npmrc has the mapping while the CI checkout does not, so installs fail only in CI.

How to fix it

Map the scope and authenticate

Add the scope-to-registry line and an auth token to .npmrc.
Reinstall so npm queries the private registry.

.npmrc

@acme:registry=https://registry.acme.internal/
//registry.acme.internal/:_authToken=${NPM_TOKEN}

How to prevent it

Commit a shared .npmrc (token via env) that maps every private scope to its registry, so local and CI resolve scoped packages identically.