The order could not be completed normally due to the following error:<br><br><em>&lt;!DOCTYPE html&gt;
&lt;html lang=&quot;en&quot;&gt;
&lt;head&gt;
  &lt;meta charset=&quot;UTF-8&quot;/&gt;
  &lt;title&gt;500 - INTERNAL ERROR&lt;/title&gt;
  &lt;base href=&quot;{{ base }}&quot;/&gt;
  &lt;link rel=&quot;stylesheet&quot; href=&quot;https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css&quot; integrity=&quot;sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2&quot; crossorigin=&quot;anonymous&quot;&gt;
  &lt;link rel=&quot;stylesheet&quot; href=&quot;https://pro.fontawesome.com/releases/v5.10.0/css/all.css&quot; integrity=&quot;sha384-AYmEC3Yw5cVb3ZcuHtOA93w35dYTsvhLPVnYs9eStHfGJvOvKxVfELGroGkvsg+p&quot; crossorigin=&quot;anonymous&quot;/&gt;
  &lt;script src=&quot;https://code.jquery.com/jquery-3.5.1.slim.min.js&quot; integrity=&quot;sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj&quot; crossorigin=&quot;anonymous&quot;&gt;&lt;/script&gt;
  &lt;script src=&quot;https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/js/bootstrap.bundle.min.js&quot; integrity=&quot;sha384-ho+j7jyWK8fNQe+A12Hb8AhRq26LrZ/JpcUGGOn+Y7RsweNrtN/tE3MoK7ZeZDyx&quot; crossorigin=&quot;anonymous&quot;&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body class=&quot;bg-light&quot;&gt;
&lt;div class=&quot;container-fluid&quot;&gt;
  &lt;div class=&quot;row justify-content-md-center mt-5&quot;&gt;
    &lt;div class=&quot;col-md-6&quot;&gt;
      &lt;div class=&quot;bg-white mt-5 p-5 m-auto text-center r-5&quot;&gt;
        &lt;div class=&quot;text-black-50 pb-3&quot;&gt;
          &lt;span class=&quot;fa fa-cogs fa-5x&quot;&gt;&lt;/span&gt;
        &lt;/div&gt;
        &lt;h5&gt;Internal Server Error!&lt;/h5&gt;
        &lt;p class=&quot;text-black-50&quot;&gt;There has been a problem loading the page you are looking for. We are working hard to resolve the issue and the page should return shortly.&lt;/p&gt;
        &lt;p&gt;If the problem persists please use the &lt;a href=&quot;index.php?route=information/contact&quot;&gt;contact us form&lt;/a&gt; for help.&lt;/p&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
&lt;/div&gt;
&lt;/body&gt;
&lt;/html&gt;</em><br><br>Double-check your SMTP settings in System > Settings > Mail, and then try disabling or uninstalling any modifications that affect customer orders (i.e. the /catalog/model/checkout/order.php file). One of those is usually the cause of errors like this.