[BUG] npm install via custom registry with path prefix does not work anymore

[zekroTJA]

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

We are using a custom npm registry which is accessible via an URL path prefix like https://example.com/npm.

After upgrading to the latest 11.3 version of npm, we noticed, that the installation process fails with the following error.

$ npm install react
npm error code E404
npm error 404 Not Found - GET https://<redacted>/react/-/react-19.1.0.tgz
npm error 404
npm error 404  'react@https://<redacted>/react/-/react-19.1.0.tgz' is not in this registry.
npm error 404
npm error 404 Note that you can also install from a
npm error 404 tarball, folder, http url, or git url.

In the logs of our registry service, we notice the path prefix /npm is missing from the package archive request.

2025-04-24T14:08:34+02:00 INFO     WebServer  GET /npm/react status=200 ttfb=0s took="343.724ms" written=2787887 rid="d052jgmr54qdharghlng"
2025-04-24T14:08:34+02:00 INFO     WebServer  GET /react/-/react-19.1.0.tgz status=404 ttfb=0s took="0.051ms" written=44 rid="d052jgmr54qdharghlo0"

When using version 10.9.2 of npm, the package archive is correctly requested with the path prefix.

2025-04-24T16:23:51+02:00 INFO     WebServer  GET /npm/react status=200 ttfb=0s took="370.604ms" written=2787887 rid="d054itur54qdhargj0lg"
2025-04-24T16:23:51+02:00 INFO     WebServer  GET /npm/react/-/react-19.1.0.tgz status=200 ttfb=0s took="0.229ms" written=24066 rid="d054itur54qdhargj0mg"

Expected Behavior

When the registry URL contains a path prefix, it should be used for downloading the package as same as in version 10.

Steps To Reproduce

Environment

• npm: 11.3.0
• Node.js: v22.14
• OS Name: Fedora Linux
• npm config:

; "user" config from /home/rhoffmann/.npmrc

@ranna-go:registry = "https://npm.pkg.github.com/"
//npm.pkg.github.com/:_authToken = (protected)

; "project" config from /home/rhoffmann/dev/test/.npmrc

registry = "https://<redacted>/npm"

; node bin location = /home/rhoffmann/.local/share/fnm/node-versions/v22.14.0/installation/bin/node
; node version = v22.14.0
; npm local prefix = /home/rhoffmann/dev/test
; npm version = 11.3.0
; cwd = /home/rhoffmann/dev/test
; HOME = /home/rhoffmann

[milaninfy]

This is fixed by #8222, you can use 11.2.0 as a workaround.