javascript - bootstrap.min.js:6 Uncaught Error: Bootstrap dropdown require Popper.js

Question

Suddenly I started to get error when I try to open my dropdown menu :

 bootstrap.min.js:6 Uncaught Error: Bootstrap dropdown require Popper.js (https://popper.js.org)
        at bootstrap.min.js:6
        at bootstrap.min.js:6
        at bootstrap.min.js:6

I am using standard bootstrap file

<script src="https://getbootstrap.com/dist/js/bootstrap.min.js">

Anything changed in bootstrap I have to take care off?

Order I am loading files is following

<script src="https://code.jquery.com/jquery-1.9.1.js"></script>
<script src="{{ STATIC_URL }}/static/jquery/jquery-1.9.1.js"></script>
<script src="https://code.jquery.com/ui/1.11.4/jquery-ui.js"></script>
<script src="{{ STATIC_URL }}/static/jquery/jquery-ui.js"></script>




<script src="https://getbootstrap.com/dist/js/bootstrap.min.js"></script>
<!-- Just to make our placeholder images work. Don't actually copy the next line! -->
<script src="https://getbootstrap.com/assets/js/vendor/holder.min.js"></script>
<!-- IE10 viewport hack for Surface/desktop Windows 8 bug -->
<script src="https://getbootstrap.com/assets/js/ie10-viewport-bug-workaround.js"></script>

Answer 1

In the introduction of Bootstrap it states which imports you need to add. https://getbootstrap.com/docs/4.0/getting-started/introduction/#quick-start

You have to add some scripts in order to get bootstrap fully working. It's important that you include them in this exact order. Popper.js is one of them:

    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>