icingaweb2/application/views/scripts/error/error.phtml

<div class="alert alert-error">
  <h1>An error occurred</h1>
  <p>
    <?php echo $this->message ?>
  </p>

  <?php if (isset($this->exception)): ?>
  <div style="text-align:left;">
    <h3>Exception information:</h3>

    <p>
      <b>Message:</b>
      <?= $this->exception->getMessage(); ?>
    </p>

    <h3>Stack trace:</h3>
    <pre>
      <?= $this->exception->getTraceAsString(); ?>
    </pre>

    <h3>Request Parameters:</h3>
      <pre><?= var_export(\Zend_Controller_Front::getInstance()->getParams(), true); ?>
    </pre>
  </div>
  <?php endif; ?>
</div>