app/views/doorkeeper/authorizations/error.html.erb
<div class="border-bottom mb-4">
<h1><%= t('doorkeeper.authorizations.error.title') %></h1>
</div>
<main role="main">
<pre>
<%= (local_assigns[:error_response] ? error_response : @pre_auth.error_response).body[:error_description] %>
</pre>
</main>