diff --git a/CMakeLists.txt b/CMakeLists.txt
index 54b9ed829..acd70dc01 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -506,6 +506,7 @@ set(TDLIB_SOURCE
   td/telegram/DialogSource.h
   td/telegram/Document.h
   td/telegram/DocumentsManager.h
+  td/telegram/DownloadManager.h
   td/telegram/DraftMessage.h
   td/telegram/EncryptedFile.h
   td/telegram/FileReferenceManager.h
diff --git a/td/telegram/DownloadManager.cpp b/td/telegram/DownloadManager.cpp
index bdde2112a..52a009477 100644
--- a/td/telegram/DownloadManager.cpp
+++ b/td/telegram/DownloadManager.cpp
@@ -4,10 +4,12 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
-#include "DownloadManager.h"
-#include "td/utils/algorithm.h"
+#include "td/telegram/DownloadManager.h"
+
 #include "td/utils/FlatHashMap.h"
+
 namespace td {
+
 class DownloadManagerImpl final : public DownloadManager {
  public:
   void set_callback(unique_ptr<Callback> callback) final {
@@ -94,7 +96,7 @@ class DownloadManagerImpl final : public DownloadManager {
     return Status::OK();
   }
 
-  Status add_file(FileId file_id, FileSourceId file_source_id, std::string search_by, int8 priority) final {
+  Status add_file(FileId file_id, FileSourceId file_source_id, string search_by, int8 priority) final {
     if (!callback_) {
       return Status::Error("TODO: code and message`");
     }
@@ -116,7 +118,7 @@ class DownloadManagerImpl final : public DownloadManager {
     return Status::OK();
   }
 
-  void search(std::string query, bool only_active, bool only_completed, std::string offset, int32 limit,
+  void search(string query, bool only_active, bool only_completed, string offset, int32 limit,
               Promise<FoundFileDownloads> promise) final {
     if (!callback_) {
       return promise.set_error(Status::Error("TODO: code and message`"));
@@ -138,11 +140,11 @@ class DownloadManagerImpl final : public DownloadManager {
     CHECK(it != active_files_.end());
     auto &file_info = it->second;
     counters_.downloaded_size -= file_info.downloaded_size;
-    counters_.total_count -= file_info.size;
+    counters_.total_size -= file_info.size;
     file_info.size = size;
     file_info.downloaded_size = download_size;
     counters_.downloaded_size += file_info.downloaded_size;
-    counters_.total_count += file_info.size;
+    counters_.total_size += file_info.size;
     file_info.is_paused = is_paused;
 
     if (download_size == size) {
@@ -184,14 +186,14 @@ class DownloadManagerImpl final : public DownloadManager {
 
   Counters counters_;
 
-  void loop() override {
+  void loop() final {
     if (!callback_) {
       return;
     }
     // TODO: ???
     // TODO: load active files from db
   }
-  void tear_down() override {
+  void tear_down() final {
     callback_.reset();
   }
 };
@@ -199,7 +201,9 @@ class DownloadManagerImpl final : public DownloadManager {
 unique_ptr<DownloadManager> DownloadManager::create() {
   return make_unique<DownloadManagerImpl>();
 }
+
 tl_object_ptr<td_api::foundFileDownloads> DownloadManager::FoundFileDownloads::to_td_api() const {
   return make_tl_object<td_api::foundFileDownloads>();
 }
+
 }  // namespace td
diff --git a/td/telegram/DownloadManager.h b/td/telegram/DownloadManager.h
index 4658003d1..db0518e43 100644
--- a/td/telegram/DownloadManager.h
+++ b/td/telegram/DownloadManager.h
@@ -5,15 +5,20 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 #pragma once
-#include "td/actor/actor.h"
-#include "td/actor/PromiseFuture.h"
+
 #include "td/telegram/files/FileId.h"
 #include "td/telegram/files/FileSourceId.h"
 #include "td/telegram/td_api.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/PromiseFuture.h"
+
 #include "td/utils/common.h"
+#include "td/utils/Status.h"
 
 namespace td {
-class DownloadManager : public td::Actor {
+
+class DownloadManager : public Actor {
  public:
   // creates, but do not stats the actor
   static td::unique_ptr<DownloadManager> create();
@@ -34,8 +39,8 @@ class DownloadManager : public td::Actor {
 
   struct FoundFileDownloads {
     int32 total_count{};
-    std::vector<FileDownload> file_downloads;
-    std::string offset;
+    vector<FileDownload> file_downloads;
+    string offset;
     tl_object_ptr<td_api::foundFileDownloads> to_td_api() const;
   };
 
@@ -49,8 +54,8 @@ class DownloadManager : public td::Actor {
     virtual void delete_file(FileId file_id) = 0;
     virtual FileId dup_file_id(FileId file_id) = 0;
 
-    virtual std::string get_unique_file_id(FileId file_id) = 0;
-    virtual std::string get_file_source_serialized(FileSourceId file_source_id) = 0;
+    virtual string get_unique_file_id(FileId file_id) = 0;
+    virtual string get_file_source_serialized(FileSourceId file_source_id) = 0;
   };
 
   //
@@ -65,8 +70,8 @@ class DownloadManager : public td::Actor {
   virtual Status remove_file(FileId file_id, FileSourceId file_source_id, bool delete_from_cache) = 0;
   virtual Status remove_all_files(bool only_active, bool only_completed, bool delete_from_cache) = 0;
   // Files are always added in is_paused = false state
-  virtual Status add_file(FileId file_id, FileSourceId file_source_id, std::string search_by, int8 priority) = 0;
-  virtual void search(std::string query, bool only_active, bool only_completed, std::string offset, int32 limit,
+  virtual Status add_file(FileId file_id, FileSourceId file_source_id, string search_by, int8 priority) = 0;
+  virtual void search(std::string query, bool only_active, bool only_completed, string offset, int32 limit,
                       Promise<FoundFileDownloads> promise) = 0;
 
   //
@@ -75,4 +80,5 @@ class DownloadManager : public td::Actor {
   virtual void update_file_download_state(FileId file_id, int64 download_size, int64 size, bool is_paused) = 0;
   virtual void update_file_deleted(FileId file_id) = 0;
 };
-};  // namespace td
+
+}  // namespace td
diff --git a/td/telegram/MessagesManager.cpp b/td/telegram/MessagesManager.cpp
index ac47107cf..b2ef966bb 100644
--- a/td/telegram/MessagesManager.cpp
+++ b/td/telegram/MessagesManager.cpp
@@ -22822,16 +22822,18 @@ void MessagesManager::delete_bot_command_message_id(DialogId dialog_id, MessageI
   }
 }
 
-FileSourceId MessagesManager::get_message_file_source_id(FullMessageId full_message_id) {
-  if (td_->auth_manager_->is_bot()) {
-    return FileSourceId();
-  }
+FileSourceId MessagesManager::get_message_file_source_id(FullMessageId full_message_id, bool force) {
+  if (!force) {
+    if (td_->auth_manager_->is_bot()) {
+      return FileSourceId();
+    }
 
-  auto dialog_id = full_message_id.get_dialog_id();
-  auto message_id = full_message_id.get_message_id();
-  if (!dialog_id.is_valid() || !(message_id.is_valid() || message_id.is_valid_scheduled()) ||
-      dialog_id.get_type() == DialogType::SecretChat || !message_id.is_any_server()) {
-    return FileSourceId();
+    auto dialog_id = full_message_id.get_dialog_id();
+    auto message_id = full_message_id.get_message_id();
+    if (!dialog_id.is_valid() || !(message_id.is_valid() || message_id.is_valid_scheduled()) ||
+        dialog_id.get_type() == DialogType::SecretChat || !message_id.is_any_server()) {
+      return FileSourceId();
+    }
   }
 
   auto &file_source_id = full_message_id_to_file_source_id_[full_message_id];
@@ -39799,21 +39801,16 @@ void MessagesManager::get_current_state(vector<td_api::object_ptr<td_api::Update
 
 void MessagesManager::add_message_file_to_downloads(FullMessageId full_message_id, FileId file_id, int32 priority,
                                                     Promise<td_api::object_ptr<td_api::file>> promise) {
-  auto message = get_message_force(full_message_id, "add message file to downloads");
-  if (!message) {
-    promise.set_error(Status::Error(400, "Can't find message"));
-    return;
+  auto m = get_message_force(full_message_id, "add_message_file_to_downloads");
+  if (m == nullptr) {
+    return promise.set_error(Status::Error(400, "Message not found"));
   }
-  if (!contains(get_message_file_ids(message), file_id)) {
-    promise.set_error(Status::Error(400, "Can't find file in message"));
-    return;
-  }
-  auto search_text = get_message_search_text(message);
-  auto file_source_id = get_message_file_source_id(full_message_id);
-  if (!file_source_id.is_valid()) {
-    promise.set_error(Status::Error(400, "Can't get file source"));
-    return;
+  if (!contains(get_message_file_ids(m), file_id)) {
+    return promise.set_error(Status::Error(400, "Message has no specified file"));
   }
+  auto search_text = get_message_search_text(m);
+  auto file_source_id = get_message_file_source_id(full_message_id, true);
+  CHECK(file_source_id.is_valid());
   TRY_STATUS_PROMISE(promise, td_->download_manager_->add_file(file_id, file_source_id, std::move(search_text),
                                                                static_cast<int8>(priority)));
   promise.set_value(td_->file_manager_->get_file_object(file_id));
diff --git a/td/telegram/MessagesManager.h b/td/telegram/MessagesManager.h
index 45132c098..02046978a 100644
--- a/td/telegram/MessagesManager.h
+++ b/td/telegram/MessagesManager.h
@@ -922,7 +922,7 @@ class MessagesManager final : public Actor {
                                vector<tl_object_ptr<telegram_api::User>> users,
                                vector<tl_object_ptr<telegram_api::Chat>> chats);
 
-  FileSourceId get_message_file_source_id(FullMessageId full_message_id);
+  FileSourceId get_message_file_source_id(FullMessageId full_message_id, bool force = false);
 
   struct MessagePushNotificationInfo {
     NotificationGroupId group_id;
diff --git a/td/telegram/Td.cpp b/td/telegram/Td.cpp
index 3ef391682..fe9398590 100644
--- a/td/telegram/Td.cpp
+++ b/td/telegram/Td.cpp
@@ -3975,7 +3975,7 @@ void Td::init_managers() {
   // TODO: move this callback somewhere else
   class DownloadManagerCallback final : public DownloadManager::Callback {
    public:
-    DownloadManagerCallback(ActorShared<> parent) : parent_(std::move(parent)) {
+    explicit DownloadManagerCallback(ActorShared<> parent) : parent_(std::move(parent)) {
       // TODO
     }
     void update_counters(DownloadManager::Counters counters) final {
@@ -3996,11 +3996,11 @@ void Td::init_managers() {
     }
     string get_unique_file_id(FileId file_id) final {
       // TODO
-      return std::string();
+      return string();
     }
     string get_file_source_serialized(FileSourceId file_source_id) final {
       // TODO
-      return std::string();
+      return string();
     }
 
    private:
@@ -6391,7 +6391,7 @@ void Td::on_request(uint64 id, const td_api::clearAllDraftMessages &request) {
 void Td::on_request(uint64 id, const td_api::downloadFile &request) {
   auto priority = request.priority_;
   if (!(1 <= priority && priority <= 32)) {
-    return send_error_raw(id, 400, "Download priority must be in [1;32] range");
+    return send_error_raw(id, 400, "Download priority must be between 1 and 32");
   }
   auto offset = request.offset_;
   if (offset < 0) {
@@ -6489,7 +6489,7 @@ void Td::on_request(uint64 id, const td_api::getSuggestedFileName &request) {
 void Td::on_request(uint64 id, td_api::uploadFile &request) {
   auto priority = request.priority_;
   if (!(1 <= priority && priority <= 32)) {
-    return send_error_raw(id, 400, "Upload priority must be in [1;32] range");
+    return send_error_raw(id, 400, "Upload priority must be between 1 and 32");
   }
 
   auto file_type = request.file_type_ == nullptr ? FileType::Temp : get_file_type(*request.file_type_);
@@ -6550,10 +6550,10 @@ void Td::on_request(uint64 id, const td_api::deleteFile &request) {
 }
 
 void Td::on_request(uint64 id, const td_api::addFileToDownloads &request) {
-  CREATE_REQUEST_PROMISE();
   if (!(1 <= request.priority_ && request.priority_ <= 32)) {
-    promise.set_error(Status::Error(400, "Upload priority must be in [1;32] range"));
+    return send_error_raw(id, 400, "Download priority must be between 1 and 32");
   }
+  CREATE_REQUEST_PROMISE();
   messages_manager_->add_message_file_to_downloads(
       FullMessageId(DialogId(request.chat_id_), MessageId(request.message_id_)), FileId(request.file_id_, 0),
       request.priority_, std::move(promise));
@@ -6590,7 +6590,6 @@ void Td::on_request(uint64 id, td_api::searchFileDownloads &request) {
   };
   send_closure(download_manager_actor_, &DownloadManager::search, std::move(request.query_), request.only_active_,
                request.only_completed_, std::move(request.offset_), request.limit_, std::move(wrapped_promise));
-  promise.set_error(Status::Error(500, "Unsupported"));
 }
 
 void Td::on_request(uint64 id, td_api::getMessageFileType &request) {
diff --git a/tdutils/td/utils/FlatHashMapChunks.h b/tdutils/td/utils/FlatHashMapChunks.h
index 4566a6769..7ee155ef7 100644
--- a/tdutils/td/utils/FlatHashMapChunks.h
+++ b/tdutils/td/utils/FlatHashMapChunks.h
@@ -12,6 +12,7 @@
 #include "td/utils/FlatHashMapLinear.h"
 
 #include <cstddef>
+#include <cstdlib>
 #include <functional>
 #include <initializer_list>
 #include <iterator>