diff --git a/client/src/app/core/repositories/agenda/item-repository.service.ts b/client/src/app/core/repositories/agenda/item-repository.service.ts
index bb477ca69..7071a52df 100644
--- a/client/src/app/core/repositories/agenda/item-repository.service.ts
+++ b/client/src/app/core/repositories/agenda/item-repository.service.ts
@@ -273,11 +273,15 @@ export class ItemRepositoryService extends BaseRepository<ViewItem, Item> {
      * Calculates the estimated end time based on the configured start and the
      * sum of durations of all agenda items
      *
-     * @returns a Date object
+     * @returns a Date object or null
      */
     public calculateEndTime(): Date {
         const startTime = this.config.instant<number>('agenda_start_event_date_time'); // a timestamp
-        const durationTime = this.calculateDuration() * 60 * 1000; // minutes to miliseconds
+        const duration = this.calculateDuration();
+        if (!startTime || !duration) {
+            return null;
+        }
+        const durationTime = duration * 60 * 1000; // minutes to miliseconds
         return new Date(startTime + durationTime);
     }
 
diff --git a/client/src/app/site/agenda/components/agenda-list/agenda-list.component.ts b/client/src/app/site/agenda/components/agenda-list/agenda-list.component.ts
index 458b15810..d4eb33594 100644
--- a/client/src/app/site/agenda/components/agenda-list/agenda-list.component.ts
+++ b/client/src/app/site/agenda/components/agenda-list/agenda-list.component.ts
@@ -257,10 +257,16 @@ export class AgendaListComponent extends ListViewBaseComponent<ViewItem> impleme
             return '';
         }
         const durationString = this.durationService.durationToString(duration);
-        const endTimeString = this.repo
-            .calculateEndTime()
-            .toLocaleTimeString(this.translate.currentLang, { hour: 'numeric', minute: 'numeric' });
-        return `${this.translate.instant('Duration')}: ${durationString} (${this.translate.instant('Estimated end')}:
-            ${endTimeString} h)`;
+        const endTime = this.repo.calculateEndTime();
+        const result = `${this.translate.instant('Duration')}: ${durationString}`;
+        if (endTime) {
+            return (
+                result +
+                ` (${this.translate.instant('Estimated end')}:
+            ${endTime.toLocaleTimeString(this.translate.currentLang, { hour: 'numeric', minute: 'numeric' })} h)`
+            );
+        } else {
+            return result;
+        }
     }
 }