Strange problem with Facebook like code

I had added Facebook follow&like buttons to my wordpress site using a code, that I needed to put on the site using the shortcoder plugin (the buttons sit within a sidebar). The goal was, to not insert a “general code” for the entire site, but make the code page-specific. This worked, but all over sudden, the buttons do no show anymore.

Here is the code I am using:
<p><iframe style="border: none; overflow: hidden; height: 21px;" src="//www.facebook.com/plugins/like.php?locale=en_US&href=[url]&width&layout=button_count&action=like&show_faces=false&share=true&height=21" width="225" height="150" frameborder="0" scrolling="no"></iframe></p>

The culprit for the “non-show” seems to be the [url]-part of the code. This is supposed to read out the current url of the PAGE, which in the past it did without problems. As for a test: When I exchange that little snippet with a proper, single URL (using http://xxxxxxx), the Facebook buttons show up. That means: that very [url] snippet of the code stopped reading out the page’s URL.

I just do not remember, how this little snippet grabs the URL. Is that coming from somewhere else in my wordpress installation? Is that a common code? Has maybe that code lost its function after upgrading to WP 4.3? I don’t think, that this little snippet is part of a shortcoder-function, since I vaguely remember, when writing that code, that this was not part of shortcoder’s “language”.

Sorry, but I am just stuck, so any help would be most appreciated.