--- a/toolkit/content/aboutTelemetry.js
+++ b/toolkit/content/aboutTelemetry.js
@@ -2054,17 +2054,22 @@ function urlStateRestore() {
         let subcategory = document.querySelector(selector);
         showSubSection(subcategory);
       }
     }
   }
 }
 
 function openJsonInFirefoxJsonViewer(json) {
-  window.open("data:application/json;base64," + btoa(json));
+  json = unescape(encodeURIComponent(json));
+  try {
+    window.open("data:application/json;base64," + btoa(json));
+  } catch (e) {
+    show(document.querySelector(".category[value=raw-payload-section]"));
+  }
 }
 
 function onLoad() {
   window.removeEventListener("load", onLoad);
 
   // Set the text in the page header
   setupPageHeader();