diff --git a/td/telegram/NotificationManager.cpp b/td/telegram/NotificationManager.cpp
index 39041d67c..9ce681b89 100644
--- a/td/telegram/NotificationManager.cpp
+++ b/td/telegram/NotificationManager.cpp
@@ -652,7 +652,9 @@ void NotificationManager::try_reuse_notification_group_id(NotificationGroupId gr
   auto group_it = get_group(group_id);
   if (group_it != groups_.end()) {
     CHECK(group_it->first.last_notification_date == 0);
-    CHECK(group_it->second.total_count == 0);
+    LOG_CHECK(group_it->second.total_count == 0)
+        << running_get_difference_ << " " << pending_notification_update_count_ << " "
+        << pending_updates_[group_id.get()].size() << " " << group_it->first << " " << group_it->second;
     CHECK(group_it->second.notifications.empty());
     CHECK(group_it->second.pending_notifications.empty());
     CHECK(!group_it->second.is_being_loaded_from_database);
diff --git a/td/telegram/NotificationManager.h b/td/telegram/NotificationManager.h
index 3ceba6499..a5f243117 100644
--- a/td/telegram/NotificationManager.h
+++ b/td/telegram/NotificationManager.h
@@ -25,6 +25,7 @@
 #include "td/utils/logging.h"
 #include "td/utils/Status.h"
 #include "td/utils/StringBuilder.h"
+#include "td/utils/Time.h"
 
 #include <functional>
 #include <map>
@@ -140,6 +141,13 @@ class NotificationManager : public Actor {
     bool is_silent = false;
     NotificationId notification_id;
     unique_ptr<NotificationType> type;
+
+    friend StringBuilder &operator<<(StringBuilder &string_builder, const PendingNotification &pending_notification) {
+      return string_builder << "PendingNotification[" << pending_notification.notification_id << " of type "
+                            << pending_notification.type << " sent at " << pending_notification.date
+                            << " with settings from " << pending_notification.settings_dialog_id
+                            << ", is_silent = " << pending_notification.is_silent << "]";
+    }
   };
 
   struct NotificationGroup {
@@ -152,6 +160,16 @@ class NotificationManager : public Actor {
 
     double pending_notifications_flush_time = 0;
     vector<PendingNotification> pending_notifications;
+
+    friend StringBuilder &operator<<(StringBuilder &string_builder, const NotificationGroup &notification_group) {
+      return string_builder << "NotificationGroup[" << notification_group.type << " with total "
+                            << notification_group.total_count << " notifications " << notification_group.notifications
+                            << " + " << notification_group.pending_notifications
+                            << ", is_loaded_from_database = " << notification_group.is_loaded_from_database
+                            << ", is_being_loaded_from_database = " << notification_group.is_being_loaded_from_database
+                            << ", pending_notifications_flush_time = "
+                            << notification_group.pending_notifications_flush_time << ", now = " << Time::now() << "]";
+    }
   };
 
   enum class SyncState : int32 { NotSynced, Pending, Completed };
diff --git a/td/telegram/NotificationType.h b/td/telegram/NotificationType.h
index ace632309..9a62e31e3 100644
--- a/td/telegram/NotificationType.h
+++ b/td/telegram/NotificationType.h
@@ -46,6 +46,13 @@ inline StringBuilder &operator<<(StringBuilder &string_builder, const Notificati
   return notification_type.to_string_builder(string_builder);
 }
 
+inline StringBuilder &operator<<(StringBuilder &string_builder, const unique_ptr<NotificationType> &notification_type) {
+  if (notification_type == nullptr) {
+    return string_builder << "null";
+  }
+  return string_builder << *notification_type;
+}
+
 unique_ptr<NotificationType> create_new_message_notification(MessageId message_id);
 
 unique_ptr<NotificationType> create_new_secret_chat_notification();