AWS Application Load Balancer transforms all headers to lower case : <p>I've a REST API application running in two EC2 instance and was using AWS Classic Load Balancer for a long time. The clients of REST API rely on the response headers (e.g. such as <code>Location</code>). </p>

<p>I know that HTTP headers are case-insensitive by definition, however (unfortunately) some clients are ignoring this and checking the headers in a case-sensitive way (e.g. they expect <code>Location</code> to start with upper case).</p>

<p>Recently I've changed to AWS Application Load Balancer and now I see that it transforms all response headers to lower case, as a result clients are failing to handle the response properly.</p>

<p>I've couple of questions here.</p>

<ol>
<li>Is it expected behavior of Application Load Balancer?</li>
<li>Is there a way to configure it to return headers as they have been built by the application?</li>
</ol>
