diederik.beirnaert
--- a/core/lib/Drupal/Core/Form/form.api.php
+++ b/core/lib/Drupal/Core/Form/form.api.php
 * @param string $elapsed
 *   A string representing the elapsed time for the batch process, e.g.,
 *   '1 min 30 secs'.
+ * @return \Drupal\Core\Routing\RedirectResponse|null
--- a/core/lib/Drupal/Core/Form/form.api.php
+++ b/core/lib/Drupal/Core/Form/form.api.php
    ];
    $message .= \Drupal::service('renderer')->render($list);
    \Drupal::messenger()->addStatus($message);
-  }
-  else {
+
+    // Optionally, redirect if needed.
+    if (shouldRedirect()) {  // Assume shouldRedirect() is a function that determines if a redirect is necessary.
+      return new \Drupal\Core\Routing\RedirectResponse(\Drupal\Core\Url::fromRoute('example.route')->toString());
+    }
+  } else {
--- a/core/lib/Drupal/Core/Form/form.api.php
+++ b/core/lib/Drupal/Core/Form/form.api.php
    ]);
    \Drupal::messenger()->addError($message);
  }
+
+  // Return NULL explicitly if no redirection is performed.
+  return NULL;
 }

+