Copy of PrestaShop default-bootstrap theme from 1.6.0.6 doesn’t display submenus after upgrade to 1.6.0.9

I made a customized theme by copying the PrestaShop default-bootstrap theme in version 1.6.0.6. After an upgrade to 1.6.0.9 the theme will no longer show the dropdown submenus.

The reason is that after the upgrade, the default-bootstrap has been updated but my customized copy hasn’t causing some needed JS files not being loaded.

The quickest solution is to go into Advanced Parameters -> Performance and enable Move JavaScript to the end

I found information about the problem here.