diff --git a/td/telegram/Client.cpp b/td/telegram/Client.cpp
index 74be58155..9b764209b 100644
--- a/td/telegram/Client.cpp
+++ b/td/telegram/Client.cpp
@@ -659,6 +659,25 @@ td_api::object_ptr<td_api::Object> ClientManager::execute(td_api::object_ptr<td_
   return Td::static_request(std::move(request));
 }
 
+static std::atomic<ClientManager::LogMessageCallbackPtr> log_message_callback;
+
+static void log_message_callback_wrapper(int verbosity_level, CSlice message) {
+  auto callback = log_message_callback.load(std::memory_order_relaxed);
+  if (callback != nullptr) {
+    callback(verbosity_level, message.c_str());
+  }
+}
+
+void ClientManager::set_log_message_callback(int max_verbosity_level, LogMessageCallbackPtr callback) {
+  if (callback == nullptr) {
+    ::td::set_log_message_callback(max_verbosity_level, nullptr);
+    log_message_callback = nullptr;
+  } else {
+    log_message_callback = callback;
+    ::td::set_log_message_callback(max_verbosity_level, log_message_callback_wrapper);
+  }
+}
+
 ClientManager::~ClientManager() = default;
 ClientManager::ClientManager(ClientManager &&other) = default;
 ClientManager &ClientManager::operator=(ClientManager &&other) = default;
diff --git a/td/telegram/Client.h b/td/telegram/Client.h
index 47b8d67a9..5eaf480d2 100644
--- a/td/telegram/Client.h
+++ b/td/telegram/Client.h
@@ -238,6 +238,26 @@ class ClientManager final {
    */
   static td_api::object_ptr<td_api::Object> execute(td_api::object_ptr<td_api::Function> &&request);
 
+  /**
+   * A type of callback function that will be called when a message is added to the internal TDLib log.
+   *
+   * \param verbosity_level Log verbosity level with which the message was added.
+   * \param message Null-terminated string with the logged message.
+   */
+  using LogMessageCallbackPtr = void (*)(int verbosity_level, const char *message);
+
+  /**
+   * Sets the callback that will be called when a message is added to the internal TDLib log.
+   * None of the TDLib methods can be called from the callback.
+   * If message verbosity level is 0, then TDLib will crash as soon as callback returns.
+   * By default the callback is not set.
+   *
+   * \param[in] max_verbosity_level Maximum verbosity level of messages for which the callback will be called.
+   * \param[in] callback Callback that will be called when a message is added to the internal TDLib log.
+   *                     Pass nullptr to remove the callback.
+   */
+  static void set_log_message_callback(int max_verbosity_level, LogMessageCallbackPtr callback);
+
   /**
    * Destroys the client manager and all TDLib client instances managed by it.
    */
diff --git a/td/telegram/ClientJson.h b/td/telegram/ClientJson.h
index cb23b3fff..9ee879315 100644
--- a/td/telegram/ClientJson.h
+++ b/td/telegram/ClientJson.h
@@ -18,6 +18,7 @@
 
 namespace td {
 
+// TODO can be made private in TDLib 2.0
 class ClientJson final {
  public:
   void send(Slice request);
diff --git a/td/telegram/Log.cpp b/td/telegram/Log.cpp
index add941b2c..365bf6bbf 100644
--- a/td/telegram/Log.cpp
+++ b/td/telegram/Log.cpp
@@ -6,6 +6,7 @@
 //
 #include "td/telegram/Log.h"
 
+#include "td/telegram/Client.h"
 #include "td/telegram/Logging.h"
 
 #include "td/telegram/td_api.h"
@@ -23,9 +24,13 @@ static string log_file_path;
 static int64 max_log_file_size = 10 << 20;
 static Log::FatalErrorCallbackPtr fatal_error_callback;
 
-static void fatal_error_callback_wrapper(CSlice message) {
-  CHECK(fatal_error_callback != nullptr);
-  fatal_error_callback(message.c_str());
+static void fatal_error_callback_wrapper(int verbosity_level, const char *message) {
+  if (verbosity_level == 0) {
+    auto callback = fatal_error_callback;
+    if (callback != nullptr) {
+      callback(message);
+    }
+  }
 }
 
 bool Log::set_file_path(string file_path) {
@@ -59,11 +64,11 @@ void Log::set_verbosity_level(int new_verbosity_level) {
 void Log::set_fatal_error_callback(FatalErrorCallbackPtr callback) {
   std::lock_guard<std::mutex> lock(log_mutex);
   if (callback == nullptr) {
+    ClientManager::set_log_message_callback(0, nullptr);
     fatal_error_callback = nullptr;
-    set_log_fatal_error_callback(nullptr);
   } else {
     fatal_error_callback = callback;
-    set_log_fatal_error_callback(fatal_error_callback_wrapper);
+    ClientManager::set_log_message_callback(0, fatal_error_callback_wrapper);
   }
 }
 
diff --git a/td/telegram/Log.h b/td/telegram/Log.h
index f204ece7d..7573c5b8f 100644
--- a/td/telegram/Log.h
+++ b/td/telegram/Log.h
@@ -76,6 +76,7 @@ class Log {
    * The TDLib will crash as soon as callback returns.
    * By default the callback is not set.
    *
+   * \deprecated Use ClientManager::set_log_message_callback instead.
    * \param[in]  callback Callback that will be called when a fatal error happens.
    *                      Pass nullptr to remove the callback.
    */
diff --git a/td/telegram/cli.cpp b/td/telegram/cli.cpp
index de337d418..92395d8cf 100644
--- a/td/telegram/cli.cpp
+++ b/td/telegram/cli.cpp
@@ -13,7 +13,7 @@
 #include "td/net/HttpReader.h"
 
 #include "td/telegram/ClientActor.h"
-#include "td/telegram/Log.h"
+#include "td/telegram/Client.h"
 #include "td/telegram/Td.h"  // for VERBOSITY_NAME(td_requests)
 #include "td/telegram/td_api_json.h"
 
@@ -4366,8 +4366,11 @@ static void fail_signal(int sig) {
   }
 }
 
-static void on_fatal_error(const char *error) {
-  std::cerr << "Fatal error: " << error << std::endl;
+static void on_log_message(int verbosity_level, const char *message) {
+  if (verbosity_level == 0) {
+    std::cerr << "Fatal error: " << message;
+  }
+  std::cerr << "Log message: " << message;
 }
 
 void main(int argc, char **argv) {
@@ -4376,7 +4379,7 @@ void main(int argc, char **argv) {
   ignore_signal(SignalType::Pipe).ensure();
   set_signal_handler(SignalType::Error, fail_signal).ensure();
   set_signal_handler(SignalType::Abort, fail_signal).ensure();
-  Log::set_fatal_error_callback(on_fatal_error);
+  ClientManager::set_log_message_callback(0, on_log_message);
   init_openssl_threads();
 
   const char *locale_name = (std::setlocale(LC_ALL, "fr-FR") == nullptr ? "C" : "fr-FR");
diff --git a/td/telegram/td_json_client.cpp b/td/telegram/td_json_client.cpp
index 1a426e6d0..fa897d638 100644
--- a/td/telegram/td_json_client.cpp
+++ b/td/telegram/td_json_client.cpp
@@ -6,6 +6,7 @@
 //
 #include "td/telegram/td_json_client.h"
 
+#include "td/telegram/Client.h"
 #include "td/telegram/ClientJson.h"
 
 #include "td/utils/Slice.h"
@@ -45,3 +46,7 @@ const char *td_receive(double timeout) {
 const char *td_execute(const char *request) {
   return td::json_execute(td::Slice(request == nullptr ? "" : request));
 }
+
+void td_set_log_message_callback(int max_verbosity_level, td_log_message_callback_ptr callback) {
+  td::ClientManager::set_log_message_callback(max_verbosity_level, callback);
+}
diff --git a/td/telegram/td_json_client.h b/td/telegram/td_json_client.h
index d72ff4c79..f2b8e09e2 100644
--- a/td/telegram/td_json_client.h
+++ b/td/telegram/td_json_client.h
@@ -156,6 +156,26 @@ TDJSON_EXPORT const char *td_receive(double timeout);
  */
 TDJSON_EXPORT const char *td_execute(const char *request);
 
+/**
+ * A type of callback function that will be called when a message is added to the internal TDLib log.
+ *
+ * \param verbosity_level Log verbosity level with which the message was added.
+ * \param message Null-terminated string with the logged message.
+ */
+typedef void (*td_log_message_callback_ptr)(int verbosity_level, const char *message);
+
+/**
+ * Sets the callback that will be called when a message is added to the internal TDLib log.
+ * None of the TDLib methods can be called from the callback.
+ * If message verbosity level is 0, then TDLib will crash as soon as callback returns.
+ * By default the callback is not set.
+ *
+ * \param[in] max_verbosity_level Maximum verbosity level of messages for which the callback will be called.
+ * \param[in] callback Callback that will be called when a message is added to the internal TDLib log.
+ *                     Pass nullptr to remove the callback.
+ */
+TDJSON_EXPORT void td_set_log_message_callback(int max_verbosity_level, td_log_message_callback_ptr callback);
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif
diff --git a/td/telegram/td_log.h b/td/telegram/td_log.h
index 24db9e9c9..a1a4bde30 100644
--- a/td/telegram/td_log.h
+++ b/td/telegram/td_log.h
@@ -71,6 +71,7 @@ typedef void (*td_log_fatal_error_callback_ptr)(const char *error_message);
  * The TDLib will crash as soon as callback returns.
  * By default the callback is not set.
  *
+ * \deprecated Use td_set_log_message_callback instead.
  * \param[in]  callback Callback that will be called when a fatal error happens.
  *                      Pass NULL to remove the callback.
  */
diff --git a/tdclientjson_export_list b/tdclientjson_export_list
index d70976f7d..51f370e6f 100644
--- a/tdclientjson_export_list
+++ b/tdclientjson_export_list
@@ -11,3 +11,4 @@ _td_create_client_id
 _td_send
 _td_receive
 _td_execute
+_td_set_log_message_callback
diff --git a/tdutils/td/utils/FileLog.cpp b/tdutils/td/utils/FileLog.cpp
index 23f1a257b..e5f9a56d8 100644
--- a/tdutils/td/utils/FileLog.cpp
+++ b/tdutils/td/utils/FileLog.cpp
@@ -74,14 +74,14 @@ void FileLog::do_append(int log_level, CSlice slice) {
   if (size_ > rotate_threshold_ || want_rotate_.load(std::memory_order_relaxed)) {
     auto status = rename(path_, PSLICE() << path_ << ".old");
     if (status.is_error()) {
-      process_fatal_error(PSLICE() << status.error() << " in " << __FILE__ << " at " << __LINE__);
+      process_fatal_error(PSLICE() << status.error() << " in " << __FILE__ << " at " << __LINE__ << '\n');
     }
     do_after_rotation();
   }
   while (!slice.empty()) {
     auto r_size = fd_.write(slice);
     if (r_size.is_error()) {
-      process_fatal_error(PSLICE() << r_size.error() << " in " << __FILE__ << " at " << __LINE__);
+      process_fatal_error(PSLICE() << r_size.error() << " in " << __FILE__ << " at " << __LINE__ << '\n');
     }
     auto written = r_size.ok();
     size_ += static_cast<int64>(written);
@@ -107,7 +107,7 @@ void FileLog::do_after_rotation() {
   fd_.close();
   auto r_fd = FileFd::open(path_, FileFd::Create | FileFd::Truncate | FileFd::Write);
   if (r_fd.is_error()) {
-    process_fatal_error(PSLICE() << r_fd.error() << " in " << __FILE__ << " at " << __LINE__);
+    process_fatal_error(PSLICE() << r_fd.error() << " in " << __FILE__ << " at " << __LINE__ << '\n');
   }
   fd_ = r_fd.move_as_ok();
   if (!Stderr().empty() && redirect_stderr_) {
diff --git a/tdutils/td/utils/check.cpp b/tdutils/td/utils/check.cpp
index 3d78954f8..f7f60c15b 100644
--- a/tdutils/td/utils/check.cpp
+++ b/tdutils/td/utils/check.cpp
@@ -16,7 +16,7 @@ namespace detail {
 void process_check_error(const char *message, const char *file, int line) {
   ::td::Logger(*log_interface, log_options, VERBOSITY_NAME(FATAL), Slice(file), line, Slice())
       << "Check `" << message << "` failed";
-  ::td::process_fatal_error(PSLICE() << "Check `" << message << "` failed in " << file << " at " << line);
+  ::td::process_fatal_error(PSLICE() << "Check `" << message << "` failed in " << file << " at " << line << '\n');
 }
 
 }  // namespace detail
diff --git a/tdutils/td/utils/logging.cpp b/tdutils/td/utils/logging.cpp
index 14cfe2ba0..6fdba8fe6 100644
--- a/tdutils/td/utils/logging.cpp
+++ b/tdutils/td/utils/logging.cpp
@@ -32,25 +32,28 @@ namespace td {
 
 LogOptions log_options;
 
-static std::atomic<int> max_callback_verbosity_level = 0;
-static std::atomic<OnLogMessageCallback> on_log_message_callback = nullptr;
+static std::atomic<int> max_callback_verbosity_level{-2};
+static std::atomic<OnLogMessageCallback> on_log_message_callback{nullptr};
 
 void set_log_message_callback(int max_verbosity_level, OnLogMessageCallback callback) {
+  if (callback == nullptr) {
+    max_verbosity_level = -2;
+  }
+
   max_callback_verbosity_level = max_verbosity_level;
   on_log_message_callback = callback;
 }
 
 void LogInterface::append(int log_level, CSlice slice) {
   do_append(log_level, slice);
-  if (log_level <= max_callback_verbosity_level.load(std::memory_order_relaxed)) {
+  if (log_level == VERBOSITY_NAME(FATAL)) {
+    process_fatal_error(slice);
+  } else if (log_level <= max_callback_verbosity_level.load(std::memory_order_relaxed)) {
     auto callback = on_log_message_callback.load(std::memory_order_relaxed);
     if (callback != nullptr) {
       callback(log_level, slice);
     }
   }
-  if (log_level == VERBOSITY_NAME(FATAL)) {
-    process_fatal_error(slice);
-  }
 }
 
 TD_THREAD_LOCAL const char *Logger::tag_ = nullptr;
@@ -286,17 +289,14 @@ static DefaultLog default_log;
 LogInterface *const default_log_interface = &default_log;
 LogInterface *log_interface = default_log_interface;
 
-static OnFatalErrorCallback on_fatal_error_callback = nullptr;
-
-void set_log_fatal_error_callback(OnFatalErrorCallback callback) {
-  on_fatal_error_callback = callback;
-}
-
 void process_fatal_error(CSlice message) {
-  auto callback = on_fatal_error_callback;
-  if (callback) {
-    callback(message);
+  if (0 <= max_callback_verbosity_level.load(std::memory_order_relaxed)) {
+    auto callback = on_log_message_callback.load(std::memory_order_relaxed);
+    if (callback != nullptr) {
+      callback(0, message);
+    }
   }
+
   std::abort();
 }
 
diff --git a/tdutils/td/utils/logging.h b/tdutils/td/utils/logging.h
index 6e5f3cc65..89ed51a2a 100644
--- a/tdutils/td/utils/logging.h
+++ b/tdutils/td/utils/logging.h
@@ -187,10 +187,6 @@ extern LogInterface *log_interface;
 
 [[noreturn]] void process_fatal_error(CSlice message);
 
-// deprecated in favor of set_log_message_callback
-using OnFatalErrorCallback = void (*)(CSlice message);
-void set_log_fatal_error_callback(OnFatalErrorCallback callback);
-
 using OnLogMessageCallback = void (*)(int verbosity_level, CSlice message);
 void set_log_message_callback(int max_verbosity_level, OnLogMessageCallback callback);