How to override Breadcrumb theme template? I have a custom theme that has base theme: classy setting in the mytheme.info.yml file. When we enable twig debugging locally, we find that the &lt;!-- BEGIN OUTPUT from 'themes/custom/mytheme/templates/navigation/breadcrumb.html.twig' --&gt; is displayed, but there are no theme suggestions available. 

This is what displayed on the page.



How can we create theme suggestions for breadcrumbs?

We tried the following in the mytheme.theme file, but it did not print out the ksm() statements. 

function mytheme_theme_suggestions_breadcrumb_alter(array &amp;$suggestions, array $variables) {
  ksm($suggestions); // this returns empty
  ksm($variables); // this only returns theme_hook_suggestion and links array
}


The code is based off of what we can do for block suggestions alters.

function mytheme_theme_suggestions_block_alter(array &amp;$suggestions, array $variables) {
  if (isset($variables['elements']['content']['#block_content'])) {
    $suggestions[] = 'block__' . $variables['elements']['content']['#block_content']-&gt;bundle();
  }
}
As mentioned by @Clive, breadcrumbs are not entities so I was not be able to get it done by adding a mytheme_theme_suggestions_breadcrumb_alter. Instead to solve the problem I had to do the following. On top of this, I ended up downloading and enabling Easy Breadcrumb to further modify the Breadcrumb


Copy the breadcrumb.html.twig file from the Classy theme into my mytheme directory
Clear cache
make any edits into the sites/themes/custom/mytheme/templates/navigation/breadcrumb.html.twig file
save and clear cache (if necessary)