Error code

npm E401

NPME401
Runtime Error Code· An error code from a programming runtime or package manager, like Node.js or npm.

What it means

Authentication is required to access this registry resource.

How to fix it

  1. Run npm login to authenticate.
  2. Check that your .npmrc contains a valid authToken for the registry.
  3. Verify the token has not expired or been revoked in the registry settings.

Not affiliated with npm. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.