diff --git a/library/Icingadb/Common/TicketLinks.php b/library/Icingadb/Common/TicketLinks.php
index 6cf7e7687..3fb01c60b 100644
--- a/library/Icingadb/Common/TicketLinks.php
+++ b/library/Icingadb/Common/TicketLinks.php
@@ -51,6 +51,6 @@ public function createTicketLinks($text): string
             return $tickets->createLinks($text);
         }
 
-        return $text;
+        return $text ?? '';
     }
 }
diff --git a/library/Icingadb/Compat/CompatObject.php b/library/Icingadb/Compat/CompatObject.php
index 1d9657db8..8434ced72 100644
--- a/library/Icingadb/Compat/CompatObject.php
+++ b/library/Icingadb/Compat/CompatObject.php
@@ -61,7 +61,7 @@ public static function fromModel(Model $object)
      */
     public function getName(): string
     {
-        return $this->object->name;
+        return $this->object->name ?? '';
     }
 
     public function fetch(): bool
diff --git a/library/Icingadb/Widget/Detail/EventDetail.php b/library/Icingadb/Widget/Detail/EventDetail.php
index aaf76082f..232d5df62 100644
--- a/library/Icingadb/Widget/Detail/EventDetail.php
+++ b/library/Icingadb/Widget/Detail/EventDetail.php
@@ -126,7 +126,9 @@ protected function assembleNotificationEvent(NotificationHistory $notification)
             new HtmlElement('h2', null, Text::create(t('Event Info'))),
             new HorizontalKeyValue(
                 t('Sent On'),
-                DateFormatter::formatDateTime($notification->send_time->getTimestamp())
+                isset($notification->send_time)
+                    ? DateFormatter::formatDateTime($notification->send_time->getTimestamp())
+                    : new EmptyState(t('n. a.'))
             )
         ];
 
@@ -240,7 +242,9 @@ protected function assembleStateChangeEvent(StateHistory $stateChange)
             new HtmlElement('h2', null, Text::create(t('Event Info'))),
             new HorizontalKeyValue(
                 t('Occurred On'),
-                DateFormatter::formatDateTime($stateChange->event_time->getTimestamp())
+                isset($stateChange->event_time)
+                    ? DateFormatter::formatDateTime($stateChange->event_time->getTimestamp())
+                    : new EmptyState(t('n. a.'))
             ),
             new HorizontalKeyValue(t('Scheduling Source'), $stateChange->scheduling_source),
             new HorizontalKeyValue(t('Check Source'), $stateChange->check_source)
@@ -332,29 +336,41 @@ protected function assembleDowntimeEvent(DowntimeHistory $downtime)
             ));
         $eventInfo[] = new HorizontalKeyValue(
             t('Entered On'),
-            DateFormatter::formatDateTime($downtime->entry_time->getTimestamp())
+            isset($downtime->entry_time)
+                ? DateFormatter::formatDateTime($downtime->entry_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
         $eventInfo[] = new HorizontalKeyValue(t('Author'), [new Icon('user'), $downtime->author]);
             // TODO: The following should be presented in a specific widget (maybe just like the downtime card)
         $eventInfo[] = new HorizontalKeyValue(
             t('Triggered On'),
-            DateFormatter::formatDateTime($downtime->trigger_time->getTimestamp())
+            isset($downtime->trigger_time)
+                ? DateFormatter::formatDateTime($downtime->trigger_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
         $eventInfo[] = new HorizontalKeyValue(
             t('Scheduled Start'),
-            DateFormatter::formatDateTime($downtime->scheduled_start_time->getTimestamp())
+            isset($downtime->scheduled_start_time)
+                ? DateFormatter::formatDateTime($downtime->scheduled_start_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
         $eventInfo[] = new HorizontalKeyValue(
             t('Actual Start'),
-            DateFormatter::formatDateTime($downtime->start_time->getTimestamp())
+            isset($downtime->start_time)
+                ? DateFormatter::formatDateTime($downtime->start_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
         $eventInfo[] = new HorizontalKeyValue(
             t('Scheduled End'),
-            DateFormatter::formatDateTime($downtime->scheduled_end_time->getTimestamp())
+            isset($downtime->scheduled_end_time)
+                ? DateFormatter::formatDateTime($downtime->scheduled_end_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
         $eventInfo[] = new HorizontalKeyValue(
             t('Actual End'),
-            DateFormatter::formatDateTime($downtime->end_time->getTimestamp())
+            isset($downtime->end_time)
+                ? DateFormatter::formatDateTime($downtime->end_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
 
         if ($downtime->is_flexible) {
@@ -410,7 +426,9 @@ protected function assembleCommentEvent(CommentHistory $comment)
             ));
         $eventInfo[] = new HorizontalKeyValue(
             t('Entered On'),
-            DateFormatter::formatDateTime($comment->entry_time->getTimestamp())
+            isset($comment->entry_time)
+                ? DateFormatter::formatDateTime($comment->entry_time->getTimestamp())
+                : new EmptyState(t('n. a.'))
         );
         $eventInfo[] = new HorizontalKeyValue(t('Author'), [new Icon('user'), $comment->author]);
         $eventInfo[] = new HorizontalKeyValue(
@@ -478,7 +496,9 @@ protected function assembleFlappingEvent(FlappingHistory $flapping)
                 )),
             new HorizontalKeyValue(
                 t('Started on'),
-                DateFormatter::formatDateTime($flapping->start_time->getTimestamp())
+                isset($flapping->start_time)
+                    ? DateFormatter::formatDateTime($flapping->start_time->getTimestamp())
+                    : new EmptyState(t('n. a.'))
             )
         ];
         if ($this->event->event_type === 'flapping_start') {
@@ -520,7 +540,9 @@ protected function assembleAcknowledgeEvent(AcknowledgementHistory $acknowledgem
             new HtmlElement('h2', null, Text::create(t('Event Info'))),
             new HorizontalKeyValue(
                 t('Set on'),
-                DateFormatter::formatDateTime($acknowledgement->set_time->getTimestamp())
+                isset($acknowledgement->set_time)
+                    ? DateFormatter::formatDateTime($acknowledgement->set_time->getTimestamp())
+                    : new EmptyState(t('n. a.'))
             ),
             new HorizontalKeyValue(t('Author'), $acknowledgement->author
                 ? [new Icon('user'), $acknowledgement->author]
@@ -546,8 +568,8 @@ protected function assembleAcknowledgeEvent(AcknowledgementHistory $acknowledgem
             $eventInfo[] = new HorizontalKeyValue(
                 t('Expires On'),
                 $acknowledgement->expire_time
-                ? DateFormatter::formatDateTime($acknowledgement->expire_time->getTimestamp())
-                : new EmptyState(t('Never'))
+                    ? DateFormatter::formatDateTime($acknowledgement->expire_time->getTimestamp())
+                    : new EmptyState(t('Never'))
             );
             $eventInfo[] = new HorizontalKeyValue(t('Sticky'), isset($acknowledgement->is_sticky)
                 ? ($acknowledgement->is_sticky ? t('Yes') : t('No'))
@@ -559,7 +581,7 @@ protected function assembleAcknowledgeEvent(AcknowledgementHistory $acknowledgem
             $eventInfo[] = new HorizontalKeyValue(
                 t('Cleared on'),
                 DateFormatter::formatDateTime(
-                    $acknowledgement->clear_time
+                    $acknowledgement->clear_time !== null
                         ? $acknowledgement->clear_time->getTimestamp()
                         : $this->event->event_time->getTimestamp()
                 )
diff --git a/library/Icingadb/Widget/Detail/ObjectDetail.php b/library/Icingadb/Widget/Detail/ObjectDetail.php
index 4ba0e6984..4aacd46f9 100644
--- a/library/Icingadb/Widget/Detail/ObjectDetail.php
+++ b/library/Icingadb/Widget/Detail/ObjectDetail.php
@@ -111,7 +111,9 @@ protected function createPrintHeader()
 
         $info[] = new HorizontalKeyValue(
             t('Last State Change'),
-            DateFormatter::formatDateTime($this->object->state->last_state_change->getTimestamp())
+            isset($this->object->state->last_state_change)
+                ? DateFormatter::formatDateTime($this->object->state->last_state_change)
+                : new EmptyState(t('n. a.'))
         );
 
         return [
diff --git a/library/Icingadb/Widget/Detail/ServiceMetaInfo.php b/library/Icingadb/Widget/Detail/ServiceMetaInfo.php
index cca723763..faca1f921 100644
--- a/library/Icingadb/Widget/Detail/ServiceMetaInfo.php
+++ b/library/Icingadb/Widget/Detail/ServiceMetaInfo.php
@@ -6,6 +6,8 @@
 
 use Icinga\Date\DateFormatter;
 use Icinga\Module\Icingadb\Model\Service;
+use ipl\I18n\Translation;
+use ipl\Web\Widget\EmptyState;
 use ipl\Web\Widget\VerticalKeyValue;
 use ipl\Html\Attributes;
 use ipl\Html\BaseHtmlElement;
@@ -15,6 +17,8 @@
 
 class ServiceMetaInfo extends BaseHtmlElement
 {
+    use Translation;
+
     protected $tag = 'div';
 
     protected $defaultAttributes = ['class' => 'object-meta-info'];
@@ -33,7 +37,9 @@ protected function assemble()
             new VerticalKeyValue('service.name', $this->service->name),
             new VerticalKeyValue(
                 'last_state_change',
-                DateFormatter::formatDateTime($this->service->state->last_state_change->getTimestamp())
+                isset($this->service->state->last_state_change)
+                    ? DateFormatter::formatDateTime($this->service->state->last_state_change->getTimestamp())
+                    : (new EmptyState($this->translate('n. a.')))->setTag('span')
             )
         );
 
diff --git a/library/Icingadb/Widget/ItemList/BaseHistoryListItem.php b/library/Icingadb/Widget/ItemList/BaseHistoryListItem.php
index 6999324d5..61da9fd1d 100644
--- a/library/Icingadb/Widget/ItemList/BaseHistoryListItem.php
+++ b/library/Icingadb/Widget/ItemList/BaseHistoryListItem.php
@@ -94,10 +94,12 @@ protected function assembleCaption(BaseHtmlElement $caption): void
                         t('State Change Rate: %.2f%%; End Threshold: %.2f%%; Flapping for %s'),
                         $this->item->flapping->percent_state_change_end,
                         $this->item->flapping->flapping_threshold_low,
-                        DateFormatter::formatDuration(
-                            $this->item->flapping->end_time->getTimestamp()
-                            - $this->item->flapping->start_time->getTimestamp()
-                        )
+                        isset($this->item->flapping->end_time)
+                            ? DateFormatter::formatDuration(
+                                $this->item->flapping->end_time->getTimestamp()
+                                - $this->item->flapping->start_time->getTimestamp()
+                            )
+                            : t('n. a.')
                     ))
                     ->getAttributes()
                     ->add('class', 'plugin-output');
@@ -345,10 +347,10 @@ protected function assembleTitle(BaseHtmlElement $title): void
 
                 break;
             case 'notification':
-                $subjectLabel = sprintf(
+                $subjectLabel = isset($this->item->notification->type) ? sprintf(
                     NotificationListItem::phraseForType($this->item->notification->type),
                     ucfirst($this->item->object_type)
-                );
+                ) : $this->item->event_type;
 
                 break;
             case 'state_change':
diff --git a/library/Icingadb/Widget/ItemTable/StateRowItem.php b/library/Icingadb/Widget/ItemTable/StateRowItem.php
index 7ca93921c..410ec7e76 100644
--- a/library/Icingadb/Widget/ItemTable/StateRowItem.php
+++ b/library/Icingadb/Widget/ItemTable/StateRowItem.php
@@ -77,12 +77,20 @@ protected function assembleCell(BaseHtmlElement $cell, string $path, $value)
             case $path === 'state.last_update':
             case $path === 'state.last_state_change':
                 $column = substr($path, 6);
-                $cell->addHtml(new TimeSince($this->item->state->$column->getTimestamp()));
+                $cell->addHtml(
+                    isset($this->item->state->$column)
+                        ? new TimeSince($this->item->state->$column->getTimestamp())
+                        : new EmptyState(t('n. a.'))
+                );
                 break;
             case $path === 'state.next_check':
             case $path === 'state.next_update':
                 $column = substr($path, 6);
-                $cell->addHtml(new TimeUntil($this->item->state->$column->getTimestamp()));
+                $cell->addHtml(
+                    isset($this->item->state->$column)
+                        ? new TimeUntil($this->item->state->$column->getTimestamp())
+                        : new EmptyState(t('n. a.'))
+                );
                 break;
             case $path === 'state.performance_data':
             case $path === 'state.normalized_performance_data':