diff --git a/platform/core/src/services/StudyPrefetcherService/StudyPrefetcherService.ts b/platform/core/src/services/StudyPrefetcherService/StudyPrefetcherService.ts
index 398974eb333..a6862f4859e 100644
--- a/platform/core/src/services/StudyPrefetcherService/StudyPrefetcherService.ts
+++ b/platform/core/src/services/StudyPrefetcherService/StudyPrefetcherService.ts
@@ -291,6 +291,11 @@ class StudyPrefetcherService extends PubSubService {
     }
 
     const activeViewport = viewports.get(activeViewportId);
+
+    if (!activeViewport) {
+      return;
+    }
+
     const displaySetUpdated = this._setActiveDisplaySetsUIDs(activeViewport.displaySetInstanceUIDs);
 
     if (forceRestart || displaySetUpdated) {