In the file vendor\magento\theme-frontend-luma\web\css\source_breadcrumbs.less there is this code getting called:

& when (@media-common = true) {
    .breadcrumbs {

Lets say the mixin .lib-breadcrumbs() is defined multiple times in different files. How can I figure out where the mixin which is called is located? Is there a stacktrace or something which I can look into?

  • 1
    Just run search in your IDE or in command line grep -rnw '/var/www/html/magento' -e 'lib-breadcrumbs' to find all definition of mixin. Check is there any module overwrite or theme.
    – BartZalas
    Mar 5, 2020 at 15:53
  • I already know this, but is this really the best way? Isn't there a stacktrace or log?
    – Black
    Mar 5, 2020 at 15:58
  • I don't think so, but you can check this library that is used for compilation of less files in Magento , maybe you will find something github.com/oyejorge/less.php.
    – BartZalas
    Mar 5, 2020 at 19:04

2 Answers 2


Below file


  • And what if I another module has overriden it? How do I know which one is getting used?
    – Black
    Mar 5, 2020 at 15:45
  • just type: find vendor/ -name _breadcrumbs.less
    – crz
    Mar 5, 2020 at 15:53
  • Can you explain how this command will help to identify the mixin which is called?
    – Black
    Mar 5, 2020 at 15:57
  • with this command you will find each file which possibly overrides lib-breadcrumbs.
    – crz
    Mar 5, 2020 at 15:59
  • I know, but for example in javascript I can see a stacktrace which shows me exactly where the method is located. Is there something similar in LESS? Maybe a logfile?
    – Black
    Mar 5, 2020 at 17:08

magento_root/lib/web/css/source/lib/_breadcrumbs.less This is the place where mixin defined

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