[BUG] npm update: EUNSUPPORTEDPROTOCOL

[thany]

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

Doing an npm update may result in an EUNSUPPORTEDPROTOCOL message:

npm error code EUNSUPPORTEDPROTOCOL
npm error Unsupported URL Type "link:": link:
npm error A complete log of this run can be found in: [...]

The detailed log only shows in which source file the error was thrown, which is useless for me as an end-user.

Expected Behavior

It should say where it has found this unsupported protocol.

And optionally, just ignore it. In my case, I've done a search through the node_modules directory, and found only link: instances in devDependencies, which are packages that should NOT be installed, nor updated. So it also shouldn't trip over them.

Steps To Reproduce

1. Have any package installed with a literal link: in the devDependencies. For example, vite.
2. npm update

This is irrelevant though, it should just say (generally speaking even) where it has found whatever causes an error.

Environment

• npm: 11.4.2
• Node.js: 22.16.0
• OS Name: Windows 10
• System Model Name: ?
• npm config:

prefix = "C:\\Users\\thany\\AppData\\Roaming\\npm"
legacy-peer-deps = true

[thany]

Just discovered the problem occurs when installing the latest version of eslint-plugin-yaml. So it turns out npm was trying to install some subdependency for a package I did not yet have installed. No wonder I couldn't find it.

In eslint-plugin-yaml's case, the dependency is a reference back to itself, which can safely be ignored as far as installation goes. But what's more, a literal link: (and nothing more) can also safely be ignored because it doesn't refer to anything.