I am trying to figure out how to display the LESS file and line number pre compilation in developer tools so that I can see where I need to be editing. I have previously got this up and running with SASS on M1 but can't figure it out with M2.

I have tried both enabling Source Maps in Chrome dev tools and installed fireLESS in Firefox however I always get the compiled file output not the original LESS file.

I can see in dev/tools/grunt/configs/less.js that Sourcemaps are enabled:

options: {
        sourceMap: true,
        outputSourceFiles: true,
        strictImports: false,
        sourceMapRootpath: '/',
        dumpLineNumbers: true, // use 'comments' instead false to output line comments for source
        ieCompat: false

However this is making no difference.

  • Something I have noticed is that when adding a bespoke less file that is being shown correctly with FireLess, its the styles-l and styles-m output thats not giving me the root files. Maybe this is due to the Symlink process in compilation i'm not sure.
    – user3250
    Jun 3, 2016 at 10:54

1 Answer 1


You have to run grunt less:theme-name

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