Use custom error layout for shop offline

src/pretix/presale/templates/pretixpresale/event/offline.html

@@ -0,0 +1,28 @@
+{% extends "error.html" %}
+{% load i18n %}
+{% load static %}
+{% block title %}{% trans "Shop offline" %}{% endblock %}
+{% block content %}
+    <i class="fa fa-fw fa-power-off big-icon"></i>
+    <div class="error-details">
+        <h1>{% trans "Shop offline" %}</h1>
+        <p>{% trans "This ticket shop is currently turned off." %}</p>
+        <p>{% trans "It is only accessible to authenticated team members." %}</p>
+        <p>{% trans "Please try again later." %}</p>
+        <p class="links">
+            <a id='goback' href='#'>{% trans "Take a step back" %}</a>
+            &middot; <a id='reload' href='#'>{% trans "Try again" %}</a>
+        </p>
+        {% if request.user.is_staff and not staff_session %}
+            <form action="{% url 'control:user.sudo' %}?next={{ request.path|add:"?"|add:request.GET.urlencode|urlencode }}" method="post">
+                <p>
+                    {% csrf_token %}
+                    <button type="submit" class="btn btn-default" id="button-sudo">
+                        <i class="fa fa-id-card"></i> {% trans "Admin mode" %}
+                    </button>
+                </p>
+            </form>
+        {% endif %}
+        <img src="{% static "pretixbase/img/pretix-logo.svg" %}" class="logo"/>
+    </div>
+{% endblock %}

src/pretix/presale/utils.py

@@ -38,17 +38,16 @@
 from urllib.parse import urljoin
 
 from django.conf import settings
-from django.core.exceptions import PermissionDenied
 from django.db.models import Q
-from django.http import Http404
+from django.http import Http404, HttpResponseForbidden
 from django.middleware.csrf import rotate_token
+from django.template import loader
 from django.template.response import TemplateResponse
 from django.urls import resolve
 from django.utils.crypto import constant_time_compare
 from django.utils.functional import SimpleLazyObject
 from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
-from django.views.defaults import permission_denied
 from django_scopes import scope
 
 from pretix.base.middleware import LocaleMiddleware
@@ -325,8 +324,9 @@ def _detect_event(request, require_live=True, require_plugin=None):
                 if not can_access:
                     # Directly construct view instead of just calling `raise` since this case is so common that we
                     # don't want it to show in our log files.
-                    return permission_denied(
-                        request, PermissionDenied(_('The selected ticket shop is currently not available.'))
+                    template = loader.get_template("pretixpresale/event/offline.html")
+                    return HttpResponseForbidden(
+                        template.render(request=request)
                     )
 
             if require_plugin: