Module does not work with Drupal 7.50!

@Vincent_Jo, I was able to reproduce the issue. Can you help me (and @clemens.tolboom) help you by answering the following three questions?

1) Kindly confirm that the following is the full code to embed from your D7.50 site:

<script type="text/javascript">
widgetContext = {"url":"http:\/\/prag-aktuell.cz\/webwidget?width=200\u0026height=350","width":"200","height":"350","widgetid":"web_widget_iframe_6eeec77ccfee192c40fddf904daf6136","scrolling":"auto"};
</script>
<script id="web_widget_iframe_6eeec77ccfee192c40fddf904daf6136" src="http://prag-aktuell.cz/sites/all/modules/web_widgets/iframe/web_widgets_iframe.js"></script>

2) Please test the following code (which is from my D7.44 site) on your D7.50 site, and let me know whether it works or not (I already know the answer, but I just need to confirm with a second person first):

<script type="text/javascript">
widgetContext = {"url":"https:\/\/mediography.by\/artist\/airwave\/embed-media-rating-widgets\/light-stars?width=300\u0026height=30","width":"300","height":"30","widgetid":"web_widget_iframe_0c345209d7f7ef2740e1709871b584ab","scrolling":"no"};
</script>
<script id="web_widget_iframe_0c345209d7f7ef2740e1709871b584ab" src="https://mediography.by/sites/all/modules/web_widgets/iframe/web_widgets_iframe.js"></script>

3) What version of PHP are you using?

It looks like I got lucky by not upgrading my source site to Drupal 7.50, which was because I was worried about it supporting PHP 7 vs. this module not being ready for it yet.

Anyway, I'm pretty sure at this point that the module does NOT work with D7.50. Here are my findings:

1) D7.50 (source site) embedding on D7.44 (client site) does NOT work.
2) D7.50 (source site) embedding on D7.50 (client site) does NOT work.
3) D7.50 (source site) embedding on D8.0.0 (client site on localhost) does NOT work.
4) D7.50 (source site) embedding on an empty test.html file does NOT work.
5) D7.44 (source site) embedding works everywhere like it should. I double-checked on D7.44, D7.50, D8.0.0 (localhost) & test.html.

@clemens.tolboom, can you please look into this? The module doesn't need to support PHP 7 yet, but I really think it needs to work with D7.50 asap. Thanks!

It looks like the problem was simpler than I had originally thought. All you have to do is enable the Security Kit module and disable "X-Frame-Options".

@Vincent_Jo, try 7.x-1.x-dev instead of 7.x-1.9 on your source site. TL;DR: http://jayl.ee/blog/2016/08/16/how-to-make-the-web-widgets-module-work-w...

I am using iFrame as a test and it is setting the width/height, but no content is filled in. Embedding a D7.50 widget on a D7.50 site - any suggestions on how to correct?

Thank you!

@drummondf, did you follow the instructions on my blog post per #6?