diff --git a/web/app.js b/web/app.js
index 676bef930..44e7b99f7 100644
--- a/web/app.js
+++ b/web/app.js
@@ -759,6 +759,10 @@ let PDFViewerApplication = {
     return loadingTask.promise.then((pdfDocument) => {
       this.load(pdfDocument);
     }, (exception) => {
+      if (loadingTask !== this.pdfLoadingTask) {
+        return; // Ignore errors for previously opened PDF files.
+      }
+
       let message = exception && exception.message;
       let loadingErrorMessage;
       if (exception instanceof InvalidPDFException) {