This javascript error shows up when you have bootstrap version 3.3 or lower on your website. The bootstrap javascript file needs an older version of jQuery, which is lower than version 3.
To fix it, you simply have to install the latest bootstrap 3 javascript file, which is version 3.4.1. You can download bootstrap version 3.4.1 from here : https://github.com/twbs/bootstrap/releases/download/v3.4.1/bootstrap-3.4.1-dist.zip
Go to the bootstrap.min.js file in the zip file and replace your old bootstrap.min.js file in your website with this new one and it will work fine with jQuery version 3 or later.
