diff --git a/js/scrollSpy.js b/js/scrollSpy.js
index 9d39a7c087..0632e6c330 100644
--- a/js/scrollSpy.js
+++ b/js/scrollSpy.js
@@ -38,10 +38,19 @@
          * So the first one with positive bounding rect top will be the nearest next header
          */
         if (currNavActive && i < headings.length - 1) {
-          const next = headings[i + 1].href.split('#')[1];
+          const heading = headings[i + 1];
+          const next = decodeURIComponent(heading.href.split('#')[1]);
           const nextHeader = document.getElementById(next);
-          const top = nextHeader.getBoundingClientRect().top;
-          currNavActive = top > OFFSET;
+
+          if (nextHeader) {
+            const top = nextHeader.getBoundingClientRect().top;
+            currNavActive = top > OFFSET;
+          } else {
+            console.error('Can not find header element', {
+              id: next,
+              heading,
+            });
+          }
         }
         /**
          * Stop searching once a first such header is found,
@@ -56,6 +65,7 @@
       }
     }, 100);
   };
+
   document.addEventListener('scroll', onScroll);
   document.addEventListener('resize', onScroll);
   document.addEventListener('DOMContentLoaded', function() {