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

<?php if ($this->title): ?>
<div class="controls">
<h1><?= $this->escape($title) ?></h1>
</div>
<?php endif ?>
<div class="content">
  <p><strong><?= $this->escape($message) ?></strong></p>
<?php if (isset($stackTrace)) : ?>
  <hr />
  <pre><?= $this->escape($stackTrace) ?></pre>
<?php endif ?>
<?php if (isset($this->messageBox)) : ?>
  <?= $this->messageBox->render(); ?>
<? endif ?>
</div>