popper.js v2.0 not compatible with bootstrap v4. Use v1.0 instead.

https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js

https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js.map

Popper.js official

https://popper.js.org/

HTML

<!-- Popper must included before bootstrap.min.js -->
<script src="{{ASSETS_FRONT}}js/jquery-1.12.4.min.js" ></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js.map"></script>
<script src="{{ASSETS_FRONT}}js/bootstrap.min.js"></script>

<script>
$(document).ready(function() {
    $('[data-toggle="popover"]').popover();
});
</script>