diff --git a/td/telegram/MessagesDb.cpp b/td/telegram/MessagesDb.cpp
index 7bf1fc0f..6b38ea87 100644
--- a/td/telegram/MessagesDb.cpp
+++ b/td/telegram/MessagesDb.cpp
@@ -268,7 +268,7 @@ class MessagesDbImpl : public MessagesDbSyncInterface {
     LOG(INFO) << "Add " << full_message_id << " to database";
     auto dialog_id = full_message_id.get_dialog_id();
     auto message_id = full_message_id.get_message_id();
-    CHECK(dialog_id.is_valid());
+    LOG_CHECK(dialog_id.is_valid()) << dialog_id << ' ' << message_id << ' ' << full_message_id;
     CHECK(message_id.is_valid());
     SCOPE_EXIT {
       add_message_stmt_.reset();
diff --git a/td/telegram/MessagesManager.cpp b/td/telegram/MessagesManager.cpp
index 15f4a910..7c01b1a1 100644
--- a/td/telegram/MessagesManager.cpp
+++ b/td/telegram/MessagesManager.cpp
@@ -19977,8 +19977,8 @@ FullMessageId MessagesManager::on_send_message_success(int64 random_id, MessageI
   if (date <= 0) {
     LOG(ERROR) << "Receive " << new_message_id << " in " << dialog_id << " with wrong date " << date;
   } else {
-    LOG_CHECK(sent_message->date > 0) << old_message_id << ' ' << sent_message->message_id << ' ' << sent_message->date
-                                      << ' ' << date;
+    LOG_CHECK(sent_message->date > 0) << old_message_id << ' ' << sent_message->message_id << ' ' << new_message_id
+                                      << ' ' << sent_message->date << ' ' << date;
     sent_message->date = date;
     CHECK(d->last_message_id != old_message_id);
   }
diff --git a/td/telegram/NotificationManager.cpp b/td/telegram/NotificationManager.cpp
index 2ccb3e23..8f51a45c 100644
--- a/td/telegram/NotificationManager.cpp
+++ b/td/telegram/NotificationManager.cpp
@@ -597,6 +597,13 @@ void NotificationManager::on_get_message_notifications_from_database(Notificatio
       notifications.pop_back();
     }
   }
+  auto first_message_id = get_first_message_id(group);
+  if (first_message_id.is_valid()) {
+    while (!notifications.empty() && notifications.back().type->get_message_id().get() >= first_message_id.get()) {
+      // possible if notifications was added after the database request was sent
+      notifications.pop_back();
+    }
+  }
 
   add_notifications_to_group_begin(std::move(group_it), std::move(notifications));
 
@@ -761,8 +768,7 @@ 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);
-    LOG_CHECK(group_it->second.total_count == 0)
+    LOG_CHECK(group_it->first.last_notification_date == 0 && group_it->second.total_count == 0)
         << running_get_difference_ << " " << delayed_notification_update_count_ << " "
         << unreceived_notification_update_count_ << " " << pending_updates_[group_id.get()].size() << " "
         << group_it->first << " " << group_it->second;
@@ -2091,6 +2097,7 @@ void NotificationManager::remove_temporary_notifications(NotificationGroupId gro
   }
   auto removed_notification_count = narrow_cast<int32>(old_group_size - notification_pos);
   if (removed_notification_count == 0) {
+    CHECK(get_temporary_notification_total_count(group_it->second) == 0);
     return;
   }
 
@@ -2104,7 +2111,9 @@ void NotificationManager::remove_temporary_notifications(NotificationGroupId gro
 
   vector<int32> removed_notification_ids;
   for (auto i = notification_pos; i < old_group_size; i++) {
-    CHECK(group.notifications[i].type->is_temporary());
+    LOG_CHECK(group.notifications[i].type->is_temporary())
+        << notification_pos << ' ' << i << ' ' << old_group_size << ' ' << removed_notification_count << ' '
+        << group.notifications[i] << ' ' << group << ' ' << group_it->first;
     VLOG(notifications) << "Remove temporary " << group.notifications[i] << " from " << group_id;
     auto notification_id = group.notifications[i].notification_id;
     on_notification_removed(notification_id);
@@ -2139,6 +2148,7 @@ void NotificationManager::remove_temporary_notifications(NotificationGroupId gro
       group_id, [](const td_api::object_ptr<td_api::notification> &notification) {
         return notification->get_id() == td_api::notificationTypeNewPushMessage::ID;
       });
+  CHECK(get_temporary_notification_total_count(group_it->second) == 0);
 }
 
 int32 NotificationManager::get_temporary_notification_total_count(const NotificationGroup &group) {
@@ -2326,7 +2336,8 @@ void NotificationManager::remove_call_notification(DialogId dialog_id, CallId ca
         force_flush_pending_updates(group_id, "reuse call group_id");
 
         auto group_it = get_group(group_id);
-        CHECK(group_it->first.dialog_id == dialog_id);
+        LOG_CHECK(group_it->first.dialog_id == dialog_id)
+            << group_id << ' ' << dialog_id << ' ' << group_it->first << ' ' << group_it->second;
         CHECK(group_it->first.last_notification_date == 0);
         CHECK(group_it->second.total_count == 0);
         CHECK(group_it->second.notifications.empty());
diff --git a/td/telegram/StickersManager.hpp b/td/telegram/StickersManager.hpp
index ba6dbc5c..7fc38e1f 100644
--- a/td/telegram/StickersManager.hpp
+++ b/td/telegram/StickersManager.hpp
@@ -54,6 +54,10 @@ void StickersManager::store_sticker(FileId file_id, bool in_sticker_set, StorerT
 
 template <class ParserT>
 FileId StickersManager::parse_sticker(bool in_sticker_set, ParserT &parser) {
+  if (parser.get_error() != nullptr) {
+    return FileId();
+  }
+
   auto sticker = make_unique<Sticker>();
   bool has_sticker_set_access_hash;
   bool in_sticker_set_stored;
@@ -62,10 +66,18 @@ FileId StickersManager::parse_sticker(bool in_sticker_set, ParserT &parser) {
   PARSE_FLAG(has_sticker_set_access_hash);
   PARSE_FLAG(in_sticker_set_stored);
   END_PARSE_FLAGS();
-  LOG_CHECK(in_sticker_set_stored == in_sticker_set)
-      << in_sticker_set << " " << in_sticker_set_stored << " " << parser.version() << " " << sticker->is_mask << " "
-      << has_sticker_set_access_hash << " "
-      << format::as_hex_dump<4>(parser.template fetch_string_raw<Slice>(parser.get_left_len()));
+  if (in_sticker_set_stored != in_sticker_set) {
+    Slice data = parser.template fetch_string_raw<Slice>(parser.get_left_len());
+    for (auto c : data) {
+      if (c != '\0') {
+        LOG_CHECK(in_sticker_set_stored == in_sticker_set)
+            << in_sticker_set << " " << in_sticker_set_stored << " " << parser.version() << " " << sticker->is_mask
+            << " " << has_sticker_set_access_hash << " " << format::as_hex_dump<4>(data);
+      }
+    }
+    parser.set_error("Zero sticker set is stored in the database");
+    return FileId();
+  }
   if (!in_sticker_set) {
     parse(sticker->set_id, parser);
     if (has_sticker_set_access_hash) {
@@ -215,6 +227,9 @@ void StickersManager::parse_sticker_set(StickerSet *sticker_set, ParserT &parser
     }
     for (uint32 i = 0; i < stored_sticker_count; i++) {
       auto sticker_id = parse_sticker(true, parser);
+      if (parser.get_error() != nullptr) {
+        return;
+      }
       sticker_set->sticker_ids.push_back(sticker_id);
 
       Sticker *sticker = get_sticker(sticker_id);
diff --git a/td/telegram/WebPageBlock.cpp b/td/telegram/WebPageBlock.cpp
index 8abcd3ba..f962e5e6 100644
--- a/td/telegram/WebPageBlock.cpp
+++ b/td/telegram/WebPageBlock.cpp
@@ -2201,8 +2201,9 @@ void WebPageBlock::call_impl(Type type, const WebPageBlock *ptr, F &&f) {
       return f(static_cast<const WebPageBlockRelatedArticles *>(ptr));
     case Type::Map:
       return f(static_cast<const WebPageBlockMap *>(ptr));
+    default:
+      UNREACHABLE();
   }
-  UNREACHABLE();
 }
 
 template <class StorerT>
@@ -2216,6 +2217,10 @@ template <class ParserT>
 unique_ptr<WebPageBlock> WebPageBlock::parse(ParserT &parser) {
   Type type;
   td::parse(type, parser);
+  if (static_cast<int32>(type) < 0 || static_cast<int32>(type) >= static_cast<int32>(Type::Size)) {
+    parser.set_error(PSTRING() << "Can't parse unknown BlockType " << static_cast<int32>(type));
+    return nullptr;
+  }
   unique_ptr<WebPageBlock> res;
   call_impl(type, nullptr, [&](const auto *ptr) {
     using ObjT = std::decay_t<decltype(*ptr)>;
diff --git a/td/telegram/WebPageBlock.h b/td/telegram/WebPageBlock.h
index bde0267e..ef28ee01 100644
--- a/td/telegram/WebPageBlock.h
+++ b/td/telegram/WebPageBlock.h
@@ -51,7 +51,8 @@ class WebPageBlock {
     Table,
     Details,
     RelatedArticles,
-    Map
+    Map,
+    Size
   };
 
   virtual Type get_type() const = 0;
diff --git a/tdutils/td/utils/Hints.cpp b/tdutils/td/utils/Hints.cpp
index 0d817f35..a9180e3a 100644
--- a/tdutils/td/utils/Hints.cpp
+++ b/tdutils/td/utils/Hints.cpp
@@ -33,7 +33,7 @@ vector<string> Hints::fix_words(vector<string> words) {
   return words;
 }
 
-vector<string> Hints::get_words(Slice name) {
+vector<string> Hints::get_words(Slice name, bool is_search) {
   bool in_word = false;
   string word;
   vector<string> words;
@@ -41,7 +41,7 @@ vector<string> Hints::get_words(Slice name) {
   auto end = name.uend();
   while (pos != end) {
     uint32 code;
-    pos = next_utf8_unsafe(pos, &code, "get_words");
+    pos = next_utf8_unsafe(pos, &code, is_search ? "get_words_search" : "get_words_add");
 
     code = prepare_search_character(code);
     if (code == 0) {
@@ -93,7 +93,7 @@ void Hints::add(KeyT key, Slice name) {
       return;
     }
     vector<string> old_transliterations;
-    for (auto &old_word : get_words(it->second)) {
+    for (auto &old_word : get_words(it->second, false)) {
       delete_word(old_word, key, word_to_keys_);
 
       for (auto &w : get_word_transliterations(old_word, false)) {
@@ -115,7 +115,7 @@ void Hints::add(KeyT key, Slice name) {
   }
 
   vector<string> transliterations;
-  for (auto &word : get_words(name)) {
+  for (auto &word : get_words(name, false)) {
     add_word(word, key, word_to_keys_);
 
     for (auto &w : get_word_transliterations(word, false)) {
@@ -166,7 +166,7 @@ std::pair<size_t, vector<Hints::KeyT>> Hints::search(Slice query, int32 limit, b
     return {key_to_name_.size(), std::move(results)};
   }
 
-  auto words = get_words(query);
+  auto words = get_words(query, true);
   if (return_all_for_empty_query && words.empty()) {
     results.reserve(key_to_name_.size());
     for (auto &it : key_to_name_) {
diff --git a/tdutils/td/utils/Hints.h b/tdutils/td/utils/Hints.h
index a5a06671..a0af1418 100644
--- a/tdutils/td/utils/Hints.h
+++ b/tdutils/td/utils/Hints.h
@@ -52,7 +52,7 @@ class Hints {
 
   static vector<string> fix_words(vector<string> words);
 
-  static vector<string> get_words(Slice name);
+  static vector<string> get_words(Slice name, bool is_search);
 
   static void add_search_results(vector<KeyT> &results, const string &word,
                                  const std::map<string, vector<KeyT>> &word_to_keys);