diff --git a/pretalx_broadcast_tools/static/pretalx_broadcast_tools/update.js b/pretalx_broadcast_tools/static/pretalx_broadcast_tools/update.js
index 95d8a43..fb27cf9 100644
--- a/pretalx_broadcast_tools/static/pretalx_broadcast_tools/update.js
+++ b/pretalx_broadcast_tools/static/pretalx_broadcast_tools/update.js
@@ -18,7 +18,7 @@ function update_lower_third() {
     }
 
     if (!event_info)  {
-        console.warn("There's no event info yet, exiting");
+        console.warn("Waiting for event info ...");
         return
     }
 
@@ -27,10 +27,17 @@ function update_lower_third() {
         return
     }
 
+    if ('error' in schedule) {
+        $('#l3title').text('Error')
+        $('#l3speaker').html(schedule['error'].join('<br>'));
+        $('#l3info_line').text('');
+        return
+    }
+
     if (schedule['rooms'].length > 1 && !schedule['rooms'].includes(room_name)) {
         $('#l3title').text('Error')
         $('#l3speaker').text('Invalid room_name. Valid names: ' + schedule['rooms'].join(', '));
-
+        $('#l3info_line').text('');
         return
     }
 
@@ -77,7 +84,11 @@ function update_schedule() {
         $('#l3box').css('background-color', data['color']);
     });
     $.getJSON('../schedule.json', function(data) {
-        console.info('schedule updated with ' + data['talks'].length + ' talks in ' + data['rooms'].length + ' rooms');
+        if ('error' in data) {
+            console.error(data['error']);
+        } else {
+            console.info('schedule updated with ' + data['talks'].length + ' talks in ' + data['rooms'].length + ' rooms');
+        }
 
         schedule = data;
 
diff --git a/pretalx_broadcast_tools/views.py b/pretalx_broadcast_tools/views.py
index 5d7475f..0725ddd 100644
--- a/pretalx_broadcast_tools/views.py
+++ b/pretalx_broadcast_tools/views.py
@@ -67,46 +67,61 @@ class BroadcastToolsScheduleView(EventPermissionRequired, ScheduleMixin, Templat
         infoline = str(
             schedule.event.settings.broadcast_tools_lower_thirds_info_string or ""
         )
-        return JsonResponse(
-            {
-                "rooms": sorted(
-                    {
-                        str(room["name"])
+        try:
+            return JsonResponse(
+                {
+                    "rooms": sorted(
+                        {
+                            str(room["name"])
+                            for day in schedule.data
+                            for room in day["rooms"]
+                        }
+                    ),
+                    "talks": [
+                        {
+                            "id": talk.submission.id,
+                            "start": talk.start.astimezone(tz).isoformat(),
+                            "end": (talk.start + dt.timedelta(minutes=talk.duration))
+                            .astimezone(tz)
+                            .isoformat(),
+                            "slug": talk.frab_slug,
+                            "title": talk.submission.title,
+                            "persons": sorted(
+                                {
+                                    person.get_display_name()
+                                    for person in talk.submission.speakers.all()
+                                }
+                            ),
+                            "track": {
+                                "color": talk.submission.track.color,
+                                "name": str(talk.submission.track.name),
+                            }
+                            if talk.submission.track
+                            else None,
+                            "room": str(room["name"]),
+                            "infoline": infoline.format(
+                                EVENT_SLUG=str(schedule.event.slug),
+                                TALK_SLUG=talk.frab_slug,
+                                CODE=talk.submission.code,
+                            ),
+                        }
                         for day in schedule.data
                         for room in day["rooms"]
-                    }
-                ),
-                "talks": [
-                    {
-                        "id": talk.submission.id,
-                        "start": talk.start.astimezone(tz).isoformat(),
-                        "end": (talk.start + dt.timedelta(minutes=talk.duration))
-                        .astimezone(tz)
-                        .isoformat(),
-                        "slug": talk.frab_slug,
-                        "title": talk.submission.title,
-                        "persons": sorted(
-                            {
-                                person.get_display_name()
-                                for person in talk.submission.speakers.all()
-                            }
-                        ),
-                        "track": {
-                            "color": talk.submission.track.color,
-                            "name": str(talk.submission.track.name),
-                        }
-                        if talk.submission.track
-                        else None,
-                        "room": str(room["name"]),
-                        "infoline": infoline.format(
-                            EVENT_SLUG=str(schedule.event.slug),
-                            TALK_SLUG=talk.frab_slug,
-                            CODE=talk.submission.code,
-                        ),
-                    }
-                    for day in schedule.data
-                    for room in day["rooms"]
-                    for talk in room["talks"]
+                        for talk in room["talks"]
+                    ],
+                },
+            )
+        except KeyError as e:
+            key = str(e)[1:-1]
+            return JsonResponse({
+                'error': [
+                    f'Could not find value for placeholder {{{key}}} in info line.',
+                    f'If you want to use {{{key}}} without evaluating it, please use as follows: {{{{{key}}}}}',
                 ],
-            },
-        )
+            })
+        except Exception as e:
+            return JsonResponse({
+                'error': [
+                    repr(e),
+                ],
+            })