Radarr/NzbDrone.Web/_backboneApp/Shared/ErrorTemplate.html

<div class="alert alert-error">
    <button type="button" class="close" data-dismiss="alert">×</button>
    <i class="icon-warning-sign" /><strong>{{title}}</strong>
    {{#if preFormatted}}
        <pre> {{message}}</pre>
    {{else}}
        {{message}}
    {{/if}}
</div>