branch feature/ABR-68976. Apply it from root

50x.patch

diff --git a/assets/errors/50x.html b/assets/errors/50x.html
index 4468f58..c931df6 100644
--- a/assets/errors/50x.html
+++ b/assets/errors/50x.html
@@ -40,16 +40,26 @@
   <script type="text/javascript">
     var offline;

+
+    /**
+     * Remember the timestamp of page closing (or reloading).
+     */
     var seenKey = 'seen';
+    window.onbeforeunload = function(event) {
+      localStorage.setItem(seenKey, new Date().getTime());
+    };
+
+    /**
+     * Check if user has reload the page and redirect him to "/"
+     * @example
+     *   1) service error -> error page -> f5 -> redirect to /
+     *   2) service error -> error page -> CLOSE ERROR PAGE -> service error -> error page -> f5 -> redirect to /
+     */
     var seen = +localStorage.getItem(seenKey);
     if (seen && (new Date().getTime() - new Date(seen).getTime() < 2000)) {
       location.href = '/';
     }

-    window.onbeforeunload = function(event) {
-      localStorage.setItem(seenKey, new Date().getTime());
-    };
-
     loadTranslations("<%- VERSION %>", "<%- LANGS %>", offline = true)
       .then(function(translations) {
         Array.prototype.slice.call(document.getElementsByClassName("translate"))