diff --git a/core/modules/system/src/Tests/Update/UpdatePathTestBaseTest.php b/core/modules/system/src/Tests/Update/UpdatePathTestBaseTest.php
index 70e250a..ded77aa 100644
--- a/core/modules/system/src/Tests/Update/UpdatePathTestBaseTest.php
+++ b/core/modules/system/src/Tests/Update/UpdatePathTestBaseTest.php
@@ -38,6 +38,25 @@ public function testDatabaseLoaded() {
     foreach (['user', 'node', 'system', 'update_test_schema'] as $module) {
       $this->assertEqual(drupal_get_installed_schema_version($module), 8000, SafeMarkup::format('Module @module schema is 8000', ['@module' => $module]));
     }
+
+    // Ensure that all {router} entries can be unserialized. If they cannot be
+    // unserialized a notice will be thrown by PHP.
+
+    $result = \Drupal::database()->query("SELECT name, route from {router}")->fetchAllKeyed(0, 1);
+    // For the purpose of fetching the notices and displaying more helpful error
+    // messages, let's override the error handler temporarily.
+    set_error_handler(function ($severity, $message, $filename, $lineno) {
+      throw new \ErrorException($message, 0, $severity, $filename, $lineno);
+    });
+    foreach ($result as $route_name => $route) {
+      try {
+        unserialize($route);
+      }
+      catch (\Exception $e) {
+        $this->fail(sprintf('Error "%s" while unserializing route %s', $e->getMessage(), $route_name));
+      }
+    }
+
     // Before accessing the site we need to run updates first or the site might
     // be broken.
     $this->runUpdates();