how to fix - Fatal error: Uncaught Error: Call to undefined function mbconvertencoding()

<p>I use the php readability library in some of my code, and found on a new server that it was throwing the error.</p>
<pre><code>Fatal error: Uncaught Error: Call to undefined function mbconvertencoding()</code></pre>
<p>For me this was caused on Debian from php missing the extention:</p>
<pre><code>php-mbstring php7.0-mbstring</code></pre>
<p>which can be installed in debian by using the following command:</p>
<pre><code>sudo apt-get install php-mbstring</code></pre>
<p><img src="https://i.imgur.com/1QzTxPy.png" /></p>