diff --git a/apps/red-ui/src/app/modules/dossier/screens/file-preview-screen/services/pdf-viewer.service.ts b/apps/red-ui/src/app/modules/dossier/screens/file-preview-screen/services/pdf-viewer.service.ts
index 78ca8cb3f..640e6f6d8 100644
--- a/apps/red-ui/src/app/modules/dossier/screens/file-preview-screen/services/pdf-viewer.service.ts
+++ b/apps/red-ui/src/app/modules/dossier/screens/file-preview-screen/services/pdf-viewer.service.ts
@@ -85,7 +85,12 @@ export class PdfViewer {
     }
 
     private get _totalInternalPages() {
-        return this.documentViewer?.getPageCount() ?? 1;
+        try {
+            return this.documentViewer?.getPageCount() ?? 1;
+        } catch {
+            // might throw Error: getPageCount was called before the 'documentLoaded' event
+            return 1;
+        }
     }
 
     hideAnnotations(annotations: Annotation[]): void {