document.getElementsByClassName suddenly no longer working
<p>Suddenly I’m experiencing something strange with <strong>document.getElementsByClassName</strong> in my website.</p>

<p>Here is what happened:</p>

<p>I am running an aspx website on IIS7.0 where some parts of my JavaScript code uses <strong>document.getElementsByClassName</strong>.
I never experienced any problems with this on Firefox, Chrome or IE8+</p>

<p>Today, I’m migrating my website to a new server, which runs IIS7.0 as well.</p>

<p>I copied my website, and suddenly <strong>document.getElementsByClassName</strong> is not recognized any more by IE8+ (<em>it works normally in Chrome and Firefox though...</em>)</p>

<p>I know there is a workaround for this issue described here: <a href="https://stackoverflow.com/questions/7410949/javascript-document-getelementsbyclassname-compatibility-with-ie">javascript document.getElementsByClassName compatibility with IE</a> but that is not the question.</p>

<p>My question is: how is it possible that document.getElementsByClassName no longer works, while I just copied my website?</p>

<p>Is their something to be changed on the new server, IIS, … ?</p>

<p>Many thanks,</p>