diff --git a/chrome/browser/actor/actor_navigation_throttle.cc b/chrome/browser/actor/actor_navigation_throttle.cc
index ffc25626200d9..d9b3784664470 100644
--- a/chrome/browser/actor/actor_navigation_throttle.cc
+++ b/chrome/browser/actor/actor_navigation_throttle.cc
@@ -140,7 +140,17 @@ ActorNavigationThrottle::WillProcessResponse() {
   }
 
   if (!execution_engine_) {
-    return content::NavigationThrottle::PROCEED;
+    // The action-sequence-scoped WeakPtr was invalidated (the action sequence
+    // completed while this navigation was in flight). The ExecutionEngine
+    // itself is still alive for the duration of the task, so re-resolve it via
+    // task_id_ rather than failing open and skipping ShouldDeferNavigation().
+    if (actor::ActorTask* task =
+            ActorKeyedService::Get(GetProfile())->GetTask(task_id_)) {
+      execution_engine_ = task->GetExecutionEngine().GetWeakPtr();
+    }
+    if (!execution_engine_) {
+      return content::NavigationThrottle::CANCEL_AND_IGNORE;
+    }
   }
   content::NavigationThrottle::ThrottleAction action =
       execution_engine_->ShouldDeferNavigation(