diff --git a/system/Debug/Toolbar/Views/toolbar.js b/system/Debug/Toolbar/Views/toolbar.js
index ddaa2386f260..42ac7362acd7 100644
--- a/system/Debug/Toolbar/Views/toolbar.js
+++ b/system/Debug/Toolbar/Views/toolbar.js
@@ -440,7 +440,7 @@ var ciDebugBar = {
                 var debugPath = document.createElement("div"); // path
                 var childArray = startElement[0].parentNode.childNodes; // target child array
                 var parent = startElement[0].parentNode;
-                var start, end;
+                let start, end;
 
                 // setup container
                 debugDiv.classList.add("debug-view");
diff --git a/user_guide_src/source/changelogs/v4.6.4.rst b/user_guide_src/source/changelogs/v4.6.4.rst
index 31b799f69c19..c8cc53437233 100644
--- a/user_guide_src/source/changelogs/v4.6.4.rst
+++ b/user_guide_src/source/changelogs/v4.6.4.rst
@@ -45,6 +45,7 @@ Bugs Fixed
 - **Model:** Fixed a bug in ``Model::replace()`` where ``created_at`` field (when available) wasn't set correctly.
 - **Model:** Fixed a bug in ``Model::insertBatch()`` and ``Model::updateBatch()`` where casts were not applied to inserted or updated values.
 - **Toolbar:** Fixed bugs in ``Collectors\Logs`` that were preventing the "Logs" tab from appearing on the Debug Toolbar.
+- **Toolbar:** Fixed bugs in ``toolbar.js`` which caused "Uncaught TypeError" in some scenarios.
 - **Validation:** Fixed a bug in the ``FormatRules::valid_base64()`` validation rule that caused a TypeError when checking invalid base64 strings.
 
 See the repo's