diff --git a/extensions/cornerstone/src/services/ViewportService/CornerstoneViewportService.ts b/extensions/cornerstone/src/services/ViewportService/CornerstoneViewportService.ts
index c07a4de01..9c9bc5909 100644
--- a/extensions/cornerstone/src/services/ViewportService/CornerstoneViewportService.ts
+++ b/extensions/cornerstone/src/services/ViewportService/CornerstoneViewportService.ts
@@ -1062,7 +1062,7 @@ class CornerstoneViewportService extends PubSubService implements IViewportServi
         // During a resize, the slice index should remain unchanged. This is a temporary fix for
         // a larger issue regarding the definition of slice index with slab thickness.
         // We need to revisit this to make it more robust and understandable.
-        delete presentation.viewReference.sliceIndex;
+        delete presentation.viewReference?.sliceIndex;
         this.beforeResizePositionPresentations.set(viewportId, presentation);
       });
 
diff --git a/platform/ui/src/contextProviders/ViewportGridProvider.tsx b/platform/ui/src/contextProviders/ViewportGridProvider.tsx
index fe67b6350..49c9939fc 100644
--- a/platform/ui/src/contextProviders/ViewportGridProvider.tsx
+++ b/platform/ui/src/contextProviders/ViewportGridProvider.tsx
@@ -187,7 +187,7 @@ export function ViewportGridProvider({ children, service }: ViewportGridProvider
             updatedViewport?.viewportOptions
           );
 
-          const displaySetOptions = updatedViewport.displaySetOptions || [];
+          const displaySetOptions = updatedViewport?.displaySetOptions || [];
           if (!displaySetOptions.length) {
             // Copy all the display set options, assuming a full set of displaySet UID's is provided.
             if (state.isHangingProtocolLayout) {