diff --git a/app.js b/app.js
index 98cb3f32..f898342e 100644
--- a/app.js
+++ b/app.js
@@ -148,6 +148,6 @@ app.get(urlPrefix + '/logout', (request, response) => {
 });
 app.use((request, _response, next) => {
     debugApp(request.url);
-    next(createError(404, 'File not found.'));
+    next(createError(404, 'File not found: ' + request.url));
 });
 export default app;
diff --git a/app.ts b/app.ts
index 7f64f741..12013c48 100644
--- a/app.ts
+++ b/app.ts
@@ -277,7 +277,7 @@ app.get(urlPrefix + '/logout', (request, response) => {
 // Catch 404 and forward to error handler
 app.use((request, _response, next) => {
   debugApp(request.url)
-  next(createError(404, 'File not found.'))
+  next(createError(404, 'File not found: ' + request.url))
 })
 
 export default app