Update nginx.conf

install/deb/nginx/nginx.conf

@@ -123,7 +123,7 @@ http {
     # Error pages
     error_page 403 /error/404.html;
     error_page 404 /error/404.html;
-    error_page 502 503 504 505 /error/50x.html;
+    error_page 500 501 502 503 504 505 /error/50x.html;
 
     # Cache settings
     proxy_cache_path /var/cache/nginx levels=2 keys_zone=cache:10m inactive=60m max_size=1024m;