diff --git a/apps/dav/lib/CalDAV/Reminder/Backend.php b/apps/dav/lib/CalDAV/Reminder/Backend.php
index 62d9c5b134..a23029e478 100644
--- a/apps/dav/lib/CalDAV/Reminder/Backend.php
+++ b/apps/dav/lib/CalDAV/Reminder/Backend.php
@@ -68,8 +68,8 @@ class Backend {
 		$query->select(['cr.*', 'co.calendardata', 'c.displayname', 'c.principaluri'])
 			->from('calendar_reminders', 'cr')
 			->where($query->expr()->lte('cr.notification_date', $query->createNamedParameter($this->timeFactory->getTime())))
-			->leftJoin('cr', 'calendarobjects', 'co', $query->expr()->eq('cr.object_id', 'co.id'))
-			->leftJoin('cr', 'calendars', 'c', $query->expr()->eq('cr.calendar_id', 'c.id'));
+			->join('cr', 'calendarobjects', 'co', $query->expr()->eq('cr.object_id', 'co.id'))
+			->join('cr', 'calendars', 'c', $query->expr()->eq('cr.calendar_id', 'c.id'));
 		$stmt = $query->execute();
 
 		return array_map(
diff --git a/apps/dav/lib/CalDAV/Reminder/ReminderService.php b/apps/dav/lib/CalDAV/Reminder/ReminderService.php
index 76b4765a4f..ee3ea07161 100644
--- a/apps/dav/lib/CalDAV/Reminder/ReminderService.php
+++ b/apps/dav/lib/CalDAV/Reminder/ReminderService.php
@@ -117,6 +117,10 @@ class ReminderService {
 				? stream_get_contents($reminder['calendardata'])
 				: $reminder['calendardata'];
 
+			if (!$calendarData) {
+				continue;
+			}
+
 			$vcalendar = $this->parseCalendarData($calendarData);
 			if (!$vcalendar) {
 				$this->backend->removeReminder($reminder['id']);
@@ -190,6 +194,10 @@ class ReminderService {
 			? stream_get_contents($objectData['calendardata'])
 			: $objectData['calendardata'];
 
+		if (!$calendarData) {
+			return;
+		}
+
 		/** @var VObject\Component\VCalendar $vcalendar */
 		$vcalendar = $this->parseCalendarData($calendarData);
 		if (!$vcalendar) {