LESS 4.6.2 causing build error

[isgeoffrey]

To reproduce:
npm i with LESS set to ^4.5.1 or 4.6.2
running build with webpack

Current behavior:
webpack unable to build frontend applicaiton due to the following error
Module not found: Error: Can't resolve 'module' in 'C:\Users\xxx\git\xxx\node_modules\less\lib\less-node'

Expected behavior:
webpack builds normally

Environment information:

• less version: 4.6.2
• nodejs version: v24.0.0
• operating system: windows & linux debian (when building in server)
• webpack: 5.64.6

Able to resolve when locking LESS to 4.5.1 in package.json

[lincolnkjy]

metoo，i use vite. less version: ^4.1.0. error is "Unexpected early exit. This happens when Promises returned by plugins cannot resolve. Unfinished hook action(s) on exit:"

[xbzhs]

metoo

[adityawrdhn]

me too

[oliver34]

me too

[Cygra]

Yes, had to lock the version to 4.5.1.

related: #4411

[Heiyanqiang]

metoo

[alexander-akait]

Because using module.exports = require('./lib/less-node/index.js').default; is a breaking change, before this package was in commonjs, now it is ECMA modules, not sure why it was under the minor, also adding exports is a breaking change too

[bressler95tops]

Exactly the same thing when using 4.6+ with invenioRDM as it uses webpack under the hood. I believe the change in 4.6 that migrated to ESM is what broke it. I'll try to lock my dependencies to 4.5.1 in the mean time, but it seems odd that backwards compatibility was not considered. I'm sure there are other software configurations that have the same dependency.

[alexander-akait]

Please update to https://github.com/webpack/less-loader/releases/tag/v12.3.2, anyway it is a breaking change and should be in the major release, not minor

[matthew-dean]

My fault! Let me try to address right away. It was not intended to be a breaking change. I added tests for both ESM and CJS imports but maybe I missed some of these patterns?

[alexander-akait]

@matthew-dean When you have dynamic require on Nodejs and run it, you will execute this line: module.exports = require('./lib/less-node/index.js').default;, but less-node/index.js code is ECMA modules, so it will not work, you should never doing such things like checking Node.js version and loading different version of a package it has a lot of shadow problems - like problems with caches, problems with memory leaking, problems with dynamic loading