404 error page

nginx_default.conf

@@ -10,7 +10,7 @@ server {
         index  index.html index.htm;
     }
 
-    error_page  404              /404.html;
+    error_page  404 500 502 503 504 /404.html;
     location = /404.html {
         root   /usr/share/nginx/html;
     }