diff --git a/test/downloadutils.mjs b/test/downloadutils.mjs
index 6d80e2153..cd2123958 100644
--- a/test/downloadutils.mjs
+++ b/test/downloadutils.mjs
@@ -88,7 +88,7 @@ async function downloadManifestFiles(manifest) {
     } catch (ex) {
       console.error(`Error during downloading of ${url}:`, ex);
       fs.writeFileSync(file, ""); // making it empty file
-      fs.writeFileSync(`${file}.error`, ex);
+      fs.writeFileSync(`${file}.error`, ex.toString());
     }
   }
 }