<div class="alert alert-primary" role="alert">
  This is a primary alert—check it out!
</div>
<div class="alert alert-secondary" role="alert">
  This is a secondary alert—check it out!
</div>
<div class="alert alert-success" role="alert">
  This is a success alert—check it out!
</div>
<div class="alert alert-danger" role="alert">
  This is a danger alert—check it out!
</div>
<div class="alert alert-warning" role="alert">
  This is a warning alert—check it out!
</div>
<div class="alert alert-info" role="alert">
  This is a info alert—check it out!
</div>
<div class="alert alert-light" role="alert">
  This is a light alert—check it out!
</div>
<div class="alert alert-dark" role="alert">
  This is a dark alert—check it out!
</div>

from django.contrib.messages import constants as messages
MESSAGE_TAGS = {
    messages.ERROR: 'danger',
}