diff -u b/core/lib/Drupal/Core/Path/PathMatcher.php b/core/lib/Drupal/Core/Path/PathMatcher.php
--- b/core/lib/Drupal/Core/Path/PathMatcher.php
+++ b/core/lib/Drupal/Core/Path/PathMatcher.php
@@ -101,7 +101,7 @@
       // route match, like on exception responses.
       if ($this->routeMatch->getRouteName()) {
         $url = Url::fromRouteMatch($this->routeMatch);
-        $this->isCurrentFrontPage = ($url->getRouteName() && $url->toString() === $this->getFrontPagePath());
+        $this->isCurrentFrontPage = ($url->getRouteName() && ltrim($url->toString()) === $this->getFrontPagePath());
       }
     }
     return $this->isCurrentFrontPage;
diff -u b/core/modules/config_translation/src/ConfigNamesMapper.php b/core/modules/config_translation/src/ConfigNamesMapper.php
--- b/core/modules/config_translation/src/ConfigNamesMapper.php
+++ b/core/modules/config_translation/src/ConfigNamesMapper.php
@@ -212,7 +212,7 @@
    * {@inheritdoc}
    */
   public function getBasePath() {
-    return Url::fromRoute($this->getBaseRouteName(), $this->getBaseRouteParameters())->toString();
+    return Url::fromRoute($this->getBaseRouteName(), ltrim($this->getBaseRouteParameters())->toString());
   }
 
   /**
@@ -249,7 +249,7 @@
    * {@inheritdoc}
    */
   public function getOverviewPath() {
-    return Url::fromRoute($this->getOverviewRouteName(), $this->getOverviewRouteParameters())->toString();
+    return Url::fromRoute($this->getOverviewRouteName(), ltrim($this->getOverviewRouteParameters())->toString());
   }
 
   /**