[logger] Start using handler callback changing_config/3 in built-in handlers

The new parameter to this function, SetOrUpdate, indicates how
unspecified configuration data fields shall be set. The rule is that
if SetOrUpdate equals set, then default values shall be used, and if
SetOrUpdate equals update, then existing configuration values shall be
used. Consequently, these examples now apply to logger_std_h and
logger_disk_log_h:

set_handler_config(default, config, #{sync_mode_qlen => 20}) sets the
value of sync_mode_qlen to 20, and resets all other (writable) fields
in the config map to their default values.

update_handler_config(default, config, #{sync_mode_qlen => 20}) sets
the value of sync_mode_qlen to 20, and leaves all other fields in the
config map unchanged.

8 files changed, 414 insertions, 147 deletions

diff --git a/lib/kernel/doc/src/logger_disk_log_h.xml b/lib/kernel/doc/src/logger_disk_log_h.xml
index dfe2ab3275..d9b941a0a9 100644
--- a/lib/kernel/doc/src/logger_disk_log_h.xml
+++ b/lib/kernel/doc/src/logger_disk_log_h.xml
@@ -66,6 +66,10 @@
 	corresponds to the <c>name</c> property in the
 	<seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso>
 	datatype.</p>
+	<p>The value is set when the handler is added, and it can not
+	  be changed in runtime.</p>
+	<p>Defaults to the same name as the handler identity, in the
+	  current directory.</p>
       </item>
       <tag><c>type</c></tag>
       <item>
@@ -73,6 +77,8 @@
 	corresponds to the <c>type</c> property in the
 	<seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso>
 	datatype.</p>
+	<p>The value is set when the handler is added, and it can not
+	  be changed in runtime.</p>
 	<p>Defaults to <c>wrap</c>.</p>
       </item>
       <tag><c>max_no_files</c></tag>
@@ -82,6 +88,8 @@
 	corresponds to the <c>MaxNoFiles</c> element in the <c>size</c> property in the
 	<seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso>
 	datatype.</p>
+	<p>The value is set when the handler is added, and it can not
+	  be changed in runtime.</p>
 	<p>Defaults to <c>10</c>.</p>
 	<p>The setting has no effect on a halt log.</p>
       </item>
@@ -93,6 +101,8 @@
 	corresponds to the <c>MaxNoBytes</c> element in the <c>size</c> property in the
 	<seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso>
 	datatype.</p>
+	<p>The value is set when the handler is added, and it can not
+	  be changed in runtime.</p>
 	<p>Defaults to <c>1048576</c> bytes for a wrap log, and
 	<c>infinity</c> for a halt log.</p>
       </item>
diff --git a/lib/kernel/doc/src/logger_std_h.xml b/lib/kernel/doc/src/logger_std_h.xml
index fcd8189bae..e156f5719b 100644
--- a/lib/kernel/doc/src/logger_std_h.xml
+++ b/lib/kernel/doc/src/logger_std_h.xml
@@ -74,7 +74,9 @@
 	  circular logging. Use the disk_log handler,
 	  <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c></seealso>,
 	  for this.</p>
-	<p> Defaults to <c>standard_io</c>.</p>
+	<p>The value is set when the handler is added, and it can not
+	  be changed in runtime.</p>
+	<p>Defaults to <c>standard_io</c>.</p>
       </item>
       <tag><c>filesync_repeat_interval</c></tag>
       <item>
diff --git a/lib/kernel/src/logger_disk_log_h.erl b/lib/kernel/src/logger_disk_log_h.erl
index a8f141f135..bb8b9f08a4 100644
--- a/lib/kernel/src/logger_disk_log_h.erl
+++ b/lib/kernel/src/logger_disk_log_h.erl
@@ -33,7 +33,7 @@
          terminate/2, code_change/3]).
 
 %% logger callbacks
--export([log/2, adding_handler/1, removing_handler/1, changing_config/2]).
+-export([log/2, adding_handler/1, removing_handler/1, changing_config/3]).
 
 %% handler internal
 -export([log_handler_info/4]).
@@ -114,9 +114,8 @@ reset(Name) ->
 %%% Handler being added
 adding_handler(#{id:=Name}=Config) ->
     case check_config(adding, Config) of
-        {ok, Config1} ->
+        {ok, #{config:=HConfig}=Config1} ->
             %% create initial handler state by merging defaults with config
-            HConfig = maps:get(config, Config1, #{}),
             HState = maps:merge(get_init_state(), HConfig),
             case logger_h_common:overload_levels_ok(HState) of
                 true ->
@@ -133,32 +132,40 @@ adding_handler(#{id:=Name}=Config) ->
 
 %%%-----------------------------------------------------------------
 %%% Updating handler config
-changing_config(OldConfig = #{id:=Name, config:=OldHConfig},
-                NewConfig = #{id:=Name, config:=NewHConfig}) ->
-    #{type:=Type, file:=File, max_no_files:=MaxFs,
-      max_no_bytes:=MaxBytes} = OldHConfig,
-    case NewHConfig of
-        #{type:=Type, file:=File, max_no_files:=MaxFs,
-          max_no_bytes:=MaxBytes} ->
-            changing_config1(OldConfig, NewConfig);
-        _ ->
-            {error,{illegal_config_change,OldConfig,NewConfig}}
-    end;
-changing_config(OldConfig, NewConfig) ->
-    {error,{illegal_config_change,OldConfig,NewConfig}}.
+changing_config(SetOrUpdate,OldConfig=#{config:=OldHConfig},NewConfig) ->
+    WriteOnce = maps:with([type,file,max_no_files,max_no_bytes],OldHConfig),
+    ReadOnly = maps:with([handler_pid,mode_tab],OldHConfig),
+    NewHConfig0 = maps:get(config, NewConfig, #{}),
+    Default =
+        case SetOrUpdate of
+            set ->
+                %% Do not reset write-once fields to defaults
+                maps:merge(get_default_config(),WriteOnce);
+            update ->
+                OldHConfig
+        end,
+
+    %% Allow (accidentially) included read-only fields - just overwrite them
+    NewHConfig = maps:merge(maps:merge(Default,NewHConfig0),ReadOnly),
+
+    %% But fail if write-once fields are changed
+    case maps:with([type,file,max_no_files,max_no_bytes],NewHConfig) of
+        WriteOnce ->
+            changing_config1(maps:get(handler_pid,OldHConfig),
+                             OldConfig,
+                             NewConfig#{config=>NewHConfig});
+        Other ->
+            {Old,New} = logger_server:diff_maps(WriteOnce,Other),
+            {error,{illegal_config_change,#{config=>Old},#{config=>New}}}
+    end.
 
-changing_config1(OldConfig=#{config:=OldHConfig}, NewConfig) ->
+changing_config1(HPid, OldConfig, NewConfig) ->
     case check_config(changing, NewConfig) of
-        {ok,NewConfig1 = #{config:=NewHConfig}} ->
-            #{handler_pid:=HPid,
-              mode_tab:=ModeTab} = OldHConfig,
-            NewHConfig1 = NewHConfig#{handler_pid=>HPid,
-                                      mode_tab=>ModeTab},
-            NewConfig2 = NewConfig1#{config=>NewHConfig1},
-            try gen_server:call(HPid, {change_config,OldConfig,NewConfig2},
+        Result = {ok,NewConfig1} ->
+            try gen_server:call(HPid, {change_config,OldConfig,NewConfig1},
                                 ?DEFAULT_CALL_TIMEOUT) of
-                ok      -> {ok,NewConfig2};
-                HError  -> HError
+                ok      -> Result;
+                Error  -> Error
             catch
                 _:{timeout,_} -> {error,handler_busy}
             end;
@@ -168,10 +175,12 @@ changing_config1(OldConfig=#{config:=OldHConfig}, NewConfig) ->
 
 check_config(adding, #{id:=Name}=Config) ->
     %% merge handler specific config data
-    HConfig = merge_default_logopts(Name, maps:get(config, Config, #{})),
-    case check_h_config(maps:to_list(HConfig)) of
+    HConfig1 = maps:get(config, Config, #{}),
+    HConfig2 = maps:merge(get_default_config(), HConfig1),
+    HConfig3 = merge_default_logopts(Name, HConfig2),
+    case check_h_config(maps:to_list(HConfig3)) of
         ok ->
-            {ok,Config#{config=>HConfig}};
+            {ok,Config#{config=>HConfig3}};
         Error ->
             Error
     end;
@@ -438,7 +447,7 @@ code_change(_OldVsn, State, _Extra) ->
 
 %%%-----------------------------------------------------------------
 %%%
-get_init_state() ->
+get_default_config() ->
      #{sync_mode_qlen              => ?SYNC_MODE_QLEN,
        drop_mode_qlen              => ?DROP_MODE_QLEN,
        flush_qlen                  => ?FLUSH_QLEN,
@@ -449,10 +458,12 @@ get_init_state() ->
        overload_kill_qlen          => ?OVERLOAD_KILL_QLEN,
        overload_kill_mem_size      => ?OVERLOAD_KILL_MEM_SIZE,
        overload_kill_restart_after => ?OVERLOAD_KILL_RESTART_AFTER,
-       dl_sync_int                 => ?CONTROLLER_SYNC_INTERVAL,
-       filesync_ok_qlen            => ?FILESYNC_OK_QLEN,
        filesync_repeat_interval    => ?FILESYNC_REPEAT_INTERVAL}.
 
+get_init_state() ->
+     #{dl_sync_int                 => ?CONTROLLER_SYNC_INTERVAL,
+       filesync_ok_qlen            => ?FILESYNC_OK_QLEN}.
+
 %%%-----------------------------------------------------------------
 %%% Add a disk_log handler to the logger.
 %%% This starts a dedicated handler process which should always
diff --git a/lib/kernel/src/logger_server.erl b/lib/kernel/src/logger_server.erl
index 9e043f9362..b7735dbcf7 100644
--- a/lib/kernel/src/logger_server.erl
+++ b/lib/kernel/src/logger_server.erl
@@ -31,6 +31,9 @@
          update_config/2, update_config/3,
          update_formatter_config/2]).
 
+%% Helper
+-export([diff_maps/2]).
+
 %% gen_server callbacks
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2]).
@@ -244,16 +247,22 @@ handle_call({change_config,SetOrUpd,HandlerId,Config0}, From,
                     update -> OldConfig
                 end,
             Config = maps:merge(Default,Config0),
-            call_h_async(
-              fun() ->
-                      call_h(Module,changing_config,[SetOrUpd,OldConfig,Config],
-                             {ok,Config})
-              end,
-              fun({ok,Config1}) ->
-                      logger_config:set(Tid,HandlerId,Config1);
-                 (Error) ->
-                      Error
-              end,From,State);
+            case check_config_change(OldConfig,Config) of
+                ok ->
+                    call_h_async(
+                      fun() ->
+                              call_h(Module,changing_config,
+                                     [SetOrUpd,OldConfig,Config],
+                                     {ok,Config})
+                      end,
+                      fun({ok,Config1}) ->
+                              logger_config:set(Tid,HandlerId,Config1);
+                         (Error) ->
+                              Error
+                      end,From,State);
+                Error ->
+                    {reply,Error,State}
+            end;
         _ ->
             {reply,{error,{not_found,HandlerId}},State}
     end;
@@ -262,16 +271,22 @@ handle_call({change_config,SetOrUpd,HandlerId,Key,Value}, From,
     case logger_config:get(Tid,HandlerId) of
         {ok,#{module:=Module}=OldConfig} ->
             Config = OldConfig#{Key=>Value},
-            call_h_async(
-              fun() ->
-                      call_h(Module,changing_config,[SetOrUpd,OldConfig,Config],
-                             {ok,Config})
-              end,
-              fun({ok,Config1}) ->
-                      logger_config:set(Tid,HandlerId,Config1);
-                 (Error) ->
-                      Error
-              end,From,State);
+            case check_config_change(OldConfig,Config) of
+                ok ->
+                    call_h_async(
+                      fun() ->
+                              call_h(Module,changing_config,
+                                     [SetOrUpd,OldConfig,Config],
+                                     {ok,Config})
+                      end,
+                      fun({ok,Config1}) ->
+                              logger_config:set(Tid,HandlerId,Config1);
+                         (Error) ->
+                              Error
+                      end,From,State);
+                Error ->
+                    {reply,Error,State}
+            end;
         _ ->
             {reply,{error,{not_found,HandlerId}},State}
     end;
@@ -486,6 +501,15 @@ check_formatter({Mod,Config}) ->
 check_formatter(Formatter) ->
     throw({invalid_formatter,Formatter}).
 
+%% When changing configuration for a handler, the id and module fields
+%% can not be changed.
+check_config_change(#{id:=Id,module:=Module},#{id:=Id,module:=Module}) ->
+    ok;
+check_config_change(OldConfig,NewConfig) ->
+    {Old,New} = logger_server:diff_maps(maps:with([id,module],OldConfig),
+                                        maps:with([id,module],NewConfig)),
+    {error,{illegal_config_change,Old,New}}.
+
 call_h(Module, Function, Args, DefRet) ->
     %% Not calling code:ensure_loaded + erlang:function_exported here,
     %% since in some rare terminal cases, the code_server might not
@@ -558,3 +582,14 @@ call_h_reply(Unexpected,State) ->
                    {process,?SERVER},
                    {message,Unexpected}]),
     {noreply,State}.
+
+%% Return two maps containing only the fields that differ.
+diff_maps(M1,M2) ->
+    diffs(lists:sort(maps:to_list(M1)),lists:sort(maps:to_list(M2)),#{},#{}).
+
+diffs([H|T1],[H|T2],D1,D2) ->
+    diffs(T1,T2,D1,D2);
+diffs([{K,V1}|T1],[{K,V2}|T2],D1,D2) ->
+    diffs(T1,T2,D1#{K=>V1},D2#{K=>V2});
+diffs([],[],D1,D2) ->
+    {D1,D2}.
diff --git a/lib/kernel/src/logger_std_h.erl b/lib/kernel/src/logger_std_h.erl
index 66fa6b6ab6..6bbf75e0ab 100644
--- a/lib/kernel/src/logger_std_h.erl
+++ b/lib/kernel/src/logger_std_h.erl
@@ -35,7 +35,7 @@
          terminate/2, code_change/3]).
 
 %% logger callbacks
--export([log/2, adding_handler/1, removing_handler/1, changing_config/2]).
+-export([log/2, adding_handler/1, removing_handler/1, changing_config/3]).
 
 %% handler internal
 -export([log_handler_info/4]).
@@ -116,9 +116,8 @@ reset(Name) ->
 %%% Handler being added
 adding_handler(#{id:=Name}=Config) ->
     case check_config(adding, Config) of
-        {ok, Config1} ->
+        {ok, #{config:=HConfig}=Config1} ->
             %% create initial handler state by merging defaults with config
-            HConfig = maps:get(config, Config1, #{}),
             HState = maps:merge(get_init_state(), HConfig),
             case logger_h_common:overload_levels_ok(HState) of
                 true ->
@@ -135,22 +134,31 @@ adding_handler(#{id:=Name}=Config) ->
 
 %%%-----------------------------------------------------------------
 %%% Updating handler config
-changing_config(OldConfig=#{id:=Name, config:=OldHConfig},
-                NewConfig=#{id:=Name}) ->
-    #{type:=Type, handler_pid:=HPid, mode_tab:=ModeTab} = OldHConfig,
-    NewHConfig = maps:get(config, NewConfig, #{}),
-    case maps:get(type, NewHConfig, Type) of
-        Type ->
-            NewHConfig1 = NewHConfig#{type=>Type,
-                                      handler_pid=>HPid,
-                                      mode_tab=>ModeTab},
-            changing_config1(HPid, OldConfig,
-                             NewConfig#{config=>NewHConfig1});
-        _ ->
-            {error,{illegal_config_change,OldConfig,NewConfig}}
-    end;
-changing_config(OldConfig, NewConfig) ->
-    {error,{illegal_config_change,OldConfig,NewConfig}}.
+changing_config(SetOrUpdate,OldConfig=#{config:=OldHConfig},NewConfig) ->
+    WriteOnce = maps:with([type],OldHConfig),
+    ReadOnly = maps:with([handler_pid,mode_tab],OldHConfig),
+    NewHConfig0 = maps:get(config, NewConfig, #{}),
+    Default =
+        case SetOrUpdate of
+            set ->
+                %% Do not reset write-once fields to defaults
+                maps:merge(get_default_config(),WriteOnce);
+            update ->
+                OldHConfig
+        end,
+
+    %% Allow (accidentially) included read-only fields - just overwrite them
+    NewHConfig = maps:merge(maps:merge(Default, NewHConfig0),ReadOnly),
+
+    %% But fail if write-once fields are changed
+    case maps:with([type],NewHConfig) of
+        WriteOnce ->
+            changing_config1(maps:get(handler_pid,OldHConfig),
+                             OldConfig,
+                             NewConfig#{config=>NewHConfig});
+        Other ->
+            {error,{illegal_config_change,#{config=>WriteOnce},#{config=>Other}}}
+    end.
 
 changing_config1(HPid, OldConfig, NewConfig) ->
     case check_config(changing, NewConfig) of
@@ -169,8 +177,7 @@ changing_config1(HPid, OldConfig, NewConfig) ->
 check_config(adding, Config) ->
     %% Merge in defaults on handler level
     HConfig0 = maps:get(config, Config, #{}),
-    HConfig = maps:merge(#{type => standard_io},
-                         HConfig0),
+    HConfig = maps:merge(get_default_config(),HConfig0),
     case check_h_config(maps:to_list(HConfig)) of
         ok ->
             {ok,Config#{config=>HConfig}};
@@ -428,8 +435,9 @@ code_change(_OldVsn, State, _Extra) ->
 
 %%%-----------------------------------------------------------------
 %%%
-get_init_state() ->
-     #{sync_mode_qlen              => ?SYNC_MODE_QLEN,
+get_default_config() ->
+     #{type                        => standard_io,
+       sync_mode_qlen              => ?SYNC_MODE_QLEN,
        drop_mode_qlen              => ?DROP_MODE_QLEN,
        flush_qlen                  => ?FLUSH_QLEN,
        burst_limit_enable          => ?BURST_LIMIT_ENABLE,
@@ -439,10 +447,12 @@ get_init_state() ->
        overload_kill_qlen          => ?OVERLOAD_KILL_QLEN,
        overload_kill_mem_size      => ?OVERLOAD_KILL_MEM_SIZE,
        overload_kill_restart_after => ?OVERLOAD_KILL_RESTART_AFTER,
-       file_ctrl_sync_int          => ?CONTROLLER_SYNC_INTERVAL,
-       filesync_ok_qlen            => ?FILESYNC_OK_QLEN,
        filesync_repeat_interval    => ?FILESYNC_REPEAT_INTERVAL}.
 
+get_init_state() ->
+    #{file_ctrl_sync_int          => ?CONTROLLER_SYNC_INTERVAL,
+      filesync_ok_qlen            => ?FILESYNC_OK_QLEN}.
+
 %%%-----------------------------------------------------------------
 %%% Add a standard handler to the logger.
 %%% This starts a dedicated handler process which should always
@@ -825,4 +835,3 @@ sync_dev(Fd, DevName, PrevSyncResult, HandlerName) ->
             logger_h_common:error_notify({HandlerName,filesync,DevName,Error}),
             Error
     end.
-
diff --git a/lib/kernel/test/logger_SUITE.erl b/lib/kernel/test/logger_SUITE.erl
index b7ccba8e70..d831d0d108 100644
--- a/lib/kernel/test/logger_SUITE.erl
+++ b/lib/kernel/test/logger_SUITE.erl
@@ -246,6 +246,18 @@ change_config(_Config) ->
     {ok,C4} = logger:get_handler_config(h1),
     C4 = C3#{custom:=new_custom},
 
+    %% Change handler config: Id and module can not be changed
+    {error,{illegal_config_change,Old,New}} =
+        logger:set_handler_config(h1,id,newid),
+    %% Check that only the faulty field is included in return
+    [{id,h1}] = maps:to_list(Old),
+    [{id,newid}] = maps:to_list(New),
+    %% Check that both fields are included when both are changed
+    {error,{illegal_config_change,
+            #{id:=h1,module:=?MODULE},
+            #{id:=newid,module:=newmodule}}} =
+        logger:set_handler_config(h1,#{id=>newid,module=>newmodule}),
+
     %% Change primary config: Single key
     PConfig0 = logger:get_primary_config(),
     ok = logger:set_primary_config(level,warning),
diff --git a/lib/kernel/test/logger_disk_log_h_SUITE.erl b/lib/kernel/test/logger_disk_log_h_SUITE.erl
index a815db14e9..34f1969e67 100644
--- a/lib/kernel/test/logger_disk_log_h_SUITE.erl
+++ b/lib/kernel/test/logger_disk_log_h_SUITE.erl
@@ -316,13 +316,29 @@ errors(Config) ->
     %%! TODO:
     %%! Check how bad log_opts are handled!
 
-    {error,{illegal_config_change,_,_}} =
-        logger:set_handler_config(Name1,
-                                  config,
-                                  #{file=>LogFile1,
-                                    type=>halt}),
-    {error,{illegal_config_change,_,_}} =
-        logger:set_handler_config(Name1,id,new),
+    {error,{illegal_config_change,
+            #{config:=#{type:=wrap}},
+            #{config:=#{type:=halt}}}} =
+        logger:update_handler_config(Name1,
+                                     config,
+                                     #{type=>halt,
+                                       file=>LogFile1}),
+
+    {error,{illegal_config_change,
+            #{config:=#{file:=LogFile1}},
+            #{config:=#{file:="newfilename"}}}} =
+        logger:update_handler_config(Name1,
+                                     config,
+                                     #{file=>"newfilename"}),
+
+    %% Read-only fields may (accidentially) be included in the change,
+    %% but it won't take effect
+    {ok,C} = logger:get_handler_config(Name1),
+    ok = logger:set_handler_config(Name1,config,
+                                   #{handler_pid=>self(),
+                                     mode_tab=>erlang:make_ref()}),
+    {ok,C} = logger:get_handler_config(Name1),
+
 
     ok = logger:remove_handler(Name1),
     {error,{not_found,Name1}} = logger:remove_handler(Name1),
@@ -403,21 +419,21 @@ config_fail(_Config) ->
                               formatter=>{?MODULE,self()}}),
     %% can't change the disk log options for a log already in use
     {error,{illegal_config_change,_,_}} =
-        logger:set_handler_config(?MODULE,config,
-                                  #{max_no_files=>2}),
+        logger:update_handler_config(?MODULE,config,
+                                     #{max_no_files=>2}),
     %% can't change name of an existing handler
     {error,{illegal_config_change,_,_}} =
-        logger:set_handler_config(?MODULE,id,bad),
+        logger:update_handler_config(?MODULE,id,bad),
     %% incorrect values of OP params
     {ok,#{config := HConfig}} = logger:get_handler_config(?MODULE),
     {error,{invalid_levels,_}} =
-        logger:set_handler_config(?MODULE,config,
-                                  HConfig#{sync_mode_qlen=>100,
-                                           flush_qlen=>99}),
+        logger:update_handler_config(?MODULE,config,
+                                     HConfig#{sync_mode_qlen=>100,
+                                              flush_qlen=>99}),
     %% invalid name of config parameter
     {error,{invalid_config,logger_disk_log_h,{filesync_rep_int,2000}}} =
-        logger:set_handler_config(?MODULE, config,
-                                  HConfig#{filesync_rep_int => 2000}),
+        logger:update_handler_config(?MODULE, config,
+                                     HConfig#{filesync_rep_int => 2000}),
     ok.
 config_fail(cleanup,_Config) ->
     logger:remove_handler(?MODULE).
@@ -459,10 +475,26 @@ reconfig(Config) ->
       log_opts := #{type := ?DISK_LOG_TYPE,
                     max_no_files := ?DISK_LOG_MAX_NO_FILES,
                     max_no_bytes := ?DISK_LOG_MAX_NO_BYTES,
-                    file := _DiskLogFile}} =
+                    file := DiskLogFile}} =
         logger_disk_log_h:info(?MODULE),
+    {ok,#{config :=
+              #{sync_mode_qlen := ?SYNC_MODE_QLEN,
+                drop_mode_qlen := ?DROP_MODE_QLEN,
+                flush_qlen := ?FLUSH_QLEN,
+                burst_limit_enable := ?BURST_LIMIT_ENABLE,
+                burst_limit_max_count := ?BURST_LIMIT_MAX_COUNT,
+                burst_limit_window_time := ?BURST_LIMIT_WINDOW_TIME,
+                overload_kill_enable := ?OVERLOAD_KILL_ENABLE,
+                overload_kill_qlen := ?OVERLOAD_KILL_QLEN,
+                overload_kill_mem_size := ?OVERLOAD_KILL_MEM_SIZE,
+                overload_kill_restart_after := ?OVERLOAD_KILL_RESTART_AFTER,
+                filesync_repeat_interval := ?FILESYNC_REPEAT_INTERVAL,
+                file := DiskLogFile,
+                max_no_files := ?DISK_LOG_MAX_NO_FILES,
+                max_no_bytes := ?DISK_LOG_MAX_NO_BYTES,
+                type := wrap} = HConfig0}} =
+        logger:get_handler_config(?MODULE),
 
-    {ok,#{config := HConfig0}} = logger:get_handler_config(?MODULE),
     HConfig1 = HConfig0#{sync_mode_qlen => 1,
                          drop_mode_qlen => 2,
                          flush_qlen => 3,
@@ -488,6 +520,29 @@ reconfig(Config) ->
       overload_kill_restart_after := infinity,
       filesync_repeat_interval := no_repeat} =
         logger_disk_log_h:info(?MODULE),
+    {ok,#{config:=HConfig1}} = logger:get_handler_config(?MODULE),
+
+    ok = logger:update_handler_config(?MODULE, config,
+                                      #{flush_qlen => ?FLUSH_QLEN}),
+    {ok,#{config:=C1}} = logger:get_handler_config(?MODULE),
+    ct:log("C1: ~p",[C1]),
+    C1 = HConfig1#{flush_qlen => ?FLUSH_QLEN},
+
+    ok = logger:set_handler_config(?MODULE, config, #{sync_mode_qlen => 1}),
+    {ok,#{config:=C2}} = logger:get_handler_config(?MODULE),
+    ct:log("C2: ~p",[C2]),
+    C2 = HConfig0#{sync_mode_qlen => 1},
+
+    ok = logger:set_handler_config(?MODULE, config, #{drop_mode_qlen => 100}),
+    {ok,#{config:=C3}} = logger:get_handler_config(?MODULE),
+    ct:log("C3: ~p",[C3]),
+    C3 = HConfig0#{drop_mode_qlen => 100},
+
+    ok = logger:update_handler_config(?MODULE, config, #{sync_mode_qlen => 1}),
+    {ok,#{config:=C4}} = logger:get_handler_config(?MODULE),
+    ct:log("C4: ~p",[C4]),
+    C4 = HConfig0#{sync_mode_qlen => 1,
+                   drop_mode_qlen => 100},
 
     ok = logger:remove_handler(?MODULE),
 
@@ -507,6 +562,43 @@ reconfig(Config) ->
                     max_no_bytes := 1024,
                     file := File}} =
         logger_disk_log_h:info(?MODULE),
+    {ok,#{config :=
+              #{type := halt,
+                max_no_files := 1,
+                max_no_bytes := 1024,
+                file := File}=HaltHConfig} = Config2} =
+        logger:get_handler_config(?MODULE),
+
+    ok = logger:update_handler_config(?MODULE, level, notice),
+    {ok,C5} = logger:get_handler_config(?MODULE),
+    ct:log("C5: ~p",[C5]),
+    C5 = Config2#{level => notice},
+
+    ok = logger:set_handler_config(?MODULE, level, info),
+    {ok,C6} = logger:get_handler_config(?MODULE),
+    ct:log("C6: ~p",[C6]),
+    C6 = Config2#{level => info},
+
+    %% You are not allowed to actively set the write once fields
+    %% (type, max_no_files, max_no_bytes, file) in runtime.
+    {error, {illegal_config_change,_,_}} =
+        logger:set_handler_config(?MODULE,config,#{type=>wrap}),
+    {error, {illegal_config_change,_,_}} =
+        logger:set_handler_config(?MODULE,config,#{max_no_files=>2}),
+    {error, {illegal_config_change,_,_}} =
+        logger:set_handler_config(?MODULE,config,#{max_no_bytes=>2048}),
+    {error, {illegal_config_change,_,_}} =
+        logger:set_handler_config(?MODULE,config,#{file=>"otherfile.log"}),
+    {ok,C7} = logger:get_handler_config(?MODULE),
+    ct:log("C7: ~p",[C7]),
+    C7 = C6,
+
+    %%  ... but if you don't specify the write once fields, then
+    %%  set_handler_config shall NOT reset them to their default value
+    ok = logger:set_handler_config(?MODULE,config,#{sync_mode_qlen=>1}),
+    {ok,#{config:=C8}} = logger:get_handler_config(?MODULE),
+    ct:log("C8: ~p",[C8]),
+    C8 = HaltHConfig#{sync_mode_qlen=>1},
     ok.
 
 reconfig(cleanup, _Config) ->
@@ -536,7 +628,7 @@ sync(Config) ->
     %% a disk_log_sync is still performed when handler goes idle
     {ok,#{config := HConfig}} = logger:get_handler_config(?MODULE),
     HConfig1 = HConfig#{filesync_repeat_interval => no_repeat},
-    ok = logger:set_handler_config(?MODULE, config, HConfig1),
+    ok = logger:update_handler_config(?MODULE, config, HConfig1),
 
     no_repeat = maps:get(filesync_repeat_interval,
                          logger_disk_log_h:info(?MODULE)),
@@ -569,13 +661,13 @@ sync(Config) ->
                  [OneSync || _ <- lists:seq(1, 1 + trunc(WaitT/SyncInt))]),
 
     HConfig2 = HConfig#{filesync_repeat_interval => SyncInt},
-    ok = logger:set_handler_config(?MODULE, config, HConfig2),
+    ok = logger:update_handler_config(?MODULE, config, HConfig2),
                       
     SyncInt = maps:get(filesync_repeat_interval,
                        logger_disk_log_h:info(?MODULE)),
     timer:sleep(WaitT),
     HConfig3 = HConfig#{filesync_repeat_interval => no_repeat},
-    ok = logger:set_handler_config(?MODULE, config, HConfig3),
+    ok = logger:update_handler_config(?MODULE, config, HConfig3),
     check_tracer(100),
     ok.
 sync(cleanup,_Config) ->
@@ -797,7 +889,7 @@ sync_failure(Config) ->
     LogOpts = maps:get(log_opts, HState),
     
     SyncInt = 500,
-    ok = rpc:call(Node, logger, set_handler_config,
+    ok = rpc:call(Node, logger, update_handler_config,
                   [?STANDARD_HANDLER, config,
                    #{filesync_repeat_interval => SyncInt}]),
     Info = rpc:call(Node, logger_disk_log_h, info, [?STANDARD_HANDLER]),
@@ -872,7 +964,7 @@ op_switch_to_sync(Config) ->
                                       drop_mode_qlen => NumOfReqs+1,
                                       flush_qlen => 2*NumOfReqs,
                                       burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Lines = count_lines(Log),
     NumOfReqs = Lines,
@@ -897,7 +989,7 @@ op_switch_to_drop(Config) ->
                                             drop_mode_qlen => 2,
                                             flush_qlen => Procs*NumOfReqs*Bursts,
                                             burst_limit_enable => false}},
-                ok = logger:set_handler_config(?MODULE, NewHConfig),
+                ok = logger:update_handler_config(?MODULE, NewHConfig),
                 %% It sometimes happens that the handler either gets
                 %% the requests in a slow enough pace so that dropping
                 %% never occurs. Therefore, lets generate a number of
@@ -943,7 +1035,7 @@ op_switch_to_flush(Config) ->
                                             drop_mode_qlen => 300,
                                             flush_qlen => 300,
                                             burst_limit_enable => false}},    
-                ok = logger:set_handler_config(?MODULE, NewHConfig),
+                ok = logger:update_handler_config(?MODULE, NewHConfig),
                 NumOfReqs = 1500,
                 Procs = 10,
                 Bursts = 10,
@@ -985,7 +1077,7 @@ limit_burst_disabled(Config) ->
                                       burst_limit_window_time => 2000,
                                       drop_mode_qlen => 200,
                                       flush_qlen => 300}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 100,
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Logged = count_lines(Log),
@@ -1005,7 +1097,7 @@ limit_burst_enabled_one(Config) ->
                                       burst_limit_window_time => 2000,
                                       drop_mode_qlen => 200,
                                       flush_qlen => 300}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 100,
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Logged = count_lines(Log),
@@ -1026,7 +1118,7 @@ limit_burst_enabled_period(Config) ->
                                       burst_limit_window_time => BurstTWin,
                                       drop_mode_qlen => 20000,
                                       flush_qlen => 20001}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     
     Windows = 3,
     Sent = send_burst({t,BurstTWin*Windows}, seq, {chars,79}, notice),
@@ -1046,7 +1138,7 @@ kill_disabled(Config) ->
         HConfig#{config=>DLHConfig#{overload_kill_enable=>false,
                                     overload_kill_qlen=>10,
                                     overload_kill_mem_size=>100}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 100,
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Logged = count_lines(Log),
@@ -1068,7 +1160,7 @@ qlen_kill_new(Config) ->
                                 overload_kill_qlen=>10,
                                 overload_kill_mem_size=>Mem0+50000,
                                 overload_kill_restart_after=>RestartAfter}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     MRef = erlang:monitor(process, Pid0),
     NumOfReqs = 100,
     Procs = 4,
@@ -1105,7 +1197,7 @@ mem_kill_new(Config) ->
                                 overload_kill_qlen=>50000,
                                 overload_kill_mem_size=>Mem0+500,
                                 overload_kill_restart_after=>RestartAfter}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     MRef = erlang:monitor(process, Pid0),
     NumOfReqs = 100,
     Procs = 4,
@@ -1139,7 +1231,7 @@ restart_after(Config) ->
         HConfig#{config=>DLHConfig#{overload_kill_enable=>true,
                                     overload_kill_qlen=>10,
                                     overload_kill_restart_after=>infinity}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig1),
+    ok = logger:update_handler_config(?MODULE, NewHConfig1),
     MRef1 = erlang:monitor(process, whereis(h_proc_name())),
     %% kill handler
     send_burst({n,100}, {spawn,4,0}, {chars,79}, notice),
@@ -1161,7 +1253,7 @@ restart_after(Config) ->
         HConfig#{config=>DLHConfig#{overload_kill_enable=>true,
                                     overload_kill_qlen=>10,
                                     overload_kill_restart_after=>RestartAfter}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig2),
+    ok = logger:update_handler_config(?MODULE, NewHConfig2),
     Pid0 = whereis(h_proc_name()),
     MRef2 = erlang:monitor(process, Pid0),
     %% kill handler
@@ -1194,7 +1286,7 @@ handler_requests_under_load(Config) ->
                                       drop_mode_qlen => 1000,
                                       flush_qlen => 2000,
                                       burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     Pid = spawn_link(fun() -> send_requests(?MODULE, 1, [{filesync,[]},
                                                          {info,[]},
                                                          {reset,[]},
@@ -1227,9 +1319,9 @@ send_requests(HName, TO, Reqs = [{Req,Res}|Rs]) ->
             Result =
                 case Req of
                     change_config ->
-                        logger:set_handler_config(HName, logger_disk_log_h,
-                                                  #{overload_kill_enable =>
-                                                        false});
+                        logger:update_handler_config(HName, logger_disk_log_h,
+                                                     #{overload_kill_enable =>
+                                                           false});
                     Func ->
                         logger_disk_log_h:Func(HName)
                 end,
diff --git a/lib/kernel/test/logger_std_h_SUITE.erl b/lib/kernel/test/logger_std_h_SUITE.erl
index 3426567bbf..c5d742ea7f 100644
--- a/lib/kernel/test/logger_std_h_SUITE.erl
+++ b/lib/kernel/test/logger_std_h_SUITE.erl
@@ -319,11 +319,10 @@ config_fail(_Config) ->
     ok = logger:add_handler(?MODULE,logger_std_h,
                             #{filter_default=>log,
                               formatter=>{?MODULE,self()}}),
-    {error,{illegal_config_change,_,_}} =
+    {error,{illegal_config_change,#{config:=#{type:=_}},#{config:=#{type:=_}}}} =
         logger:set_handler_config(?MODULE,config,
                                   #{type=>{file,"file"}}),
-    {error,{illegal_config_change,_,_}} =
-        logger:set_handler_config(?MODULE,id,bad),
+
     {error,{invalid_levels,_}} =
         logger:set_handler_config(?MODULE,config,
                                   #{sync_mode_qlen=>100,
@@ -331,6 +330,15 @@ config_fail(_Config) ->
     {error,{invalid_config,logger_std_h,{filesync_rep_int,2000}}} =
         logger:set_handler_config(?MODULE, config,
                                   #{filesync_rep_int => 2000}),
+
+    %% Read-only fields may (accidentially) be included in the change,
+    %% but it won't take effect
+    {ok,C} = logger:get_handler_config(?MODULE),
+    ok = logger:set_handler_config(?MODULE,config,
+                                   #{handler_pid=>self(),
+                                     mode_tab=>erlang:make_ref()}),
+    {ok,C} = logger:get_handler_config(?MODULE),
+
     ok.
 
 config_fail(cleanup,_Config) ->
@@ -457,9 +465,26 @@ reconfig(Config) ->
       overload_kill_qlen := ?OVERLOAD_KILL_QLEN,
       overload_kill_mem_size := ?OVERLOAD_KILL_MEM_SIZE,
       overload_kill_restart_after := ?OVERLOAD_KILL_RESTART_AFTER,
-      filesync_repeat_interval := ?FILESYNC_REPEAT_INTERVAL} =
+      filesync_repeat_interval := ?FILESYNC_REPEAT_INTERVAL} = DefaultInfo =
         logger_std_h:info(?MODULE),
 
+    {ok,
+     #{config:=
+           #{type := standard_io,
+             sync_mode_qlen := ?SYNC_MODE_QLEN,
+             drop_mode_qlen := ?DROP_MODE_QLEN,
+             flush_qlen := ?FLUSH_QLEN,
+             burst_limit_enable := ?BURST_LIMIT_ENABLE,
+             burst_limit_max_count := ?BURST_LIMIT_MAX_COUNT,
+             burst_limit_window_time := ?BURST_LIMIT_WINDOW_TIME,
+             overload_kill_enable := ?OVERLOAD_KILL_ENABLE,
+             overload_kill_qlen := ?OVERLOAD_KILL_QLEN,
+             overload_kill_mem_size := ?OVERLOAD_KILL_MEM_SIZE,
+             overload_kill_restart_after := ?OVERLOAD_KILL_RESTART_AFTER,
+             filesync_repeat_interval := ?FILESYNC_REPEAT_INTERVAL} =
+           DefaultHConf}}
+        = logger:get_handler_config(?MODULE),
+
     ok = logger:set_handler_config(?MODULE, config,
                                    #{sync_mode_qlen => 1,
                                      drop_mode_qlen => 2,
@@ -485,7 +510,77 @@ reconfig(Config) ->
       overload_kill_qlen := 100000,
       overload_kill_mem_size := 10000000,
       overload_kill_restart_after := infinity,
-      filesync_repeat_interval := no_repeat} = logger_std_h:info(?MODULE),
+      filesync_repeat_interval := no_repeat} = Info = logger_std_h:info(?MODULE),
+
+    {ok,#{config :=
+              #{type := standard_io,
+                sync_mode_qlen := 1,
+                drop_mode_qlen := 2,
+                flush_qlen := 3,
+                burst_limit_enable := false,
+                burst_limit_max_count := 10,
+                burst_limit_window_time := 10,
+                overload_kill_enable := true,
+                overload_kill_qlen := 100000,
+                overload_kill_mem_size := 10000000,
+                overload_kill_restart_after := infinity,
+                filesync_repeat_interval := no_repeat} = HConf}} =
+        logger:get_handler_config(?MODULE),
+
+    ok = logger:update_handler_config(?MODULE, config,
+                                      #{flush_qlen => ?FLUSH_QLEN}),
+    {ok,#{config:=C1}} = logger:get_handler_config(?MODULE),
+    ct:log("C1: ~p",[C1]),
+    C1 = HConf#{flush_qlen => ?FLUSH_QLEN},
+
+    ok = logger:set_handler_config(?MODULE, config, #{sync_mode_qlen => 1}),
+    {ok,#{config:=C2}} = logger:get_handler_config(?MODULE),
+    ct:log("C2: ~p",[C2]),
+    C2 = DefaultHConf#{sync_mode_qlen => 1},
+
+    ok = logger:set_handler_config(?MODULE, config, #{drop_mode_qlen => 100}),
+    {ok,#{config:=C3}} = logger:get_handler_config(?MODULE),
+    ct:log("C3: ~p",[C3]),
+    C3 = DefaultHConf#{drop_mode_qlen => 100},
+
+    ok = logger:update_handler_config(?MODULE, config, #{sync_mode_qlen => 1}),
+    {ok,#{config:=C4}} = logger:get_handler_config(?MODULE),
+    ct:log("C4: ~p",[C4]),
+    C4 = DefaultHConf#{sync_mode_qlen => 1,
+                       drop_mode_qlen => 100},
+
+    ok = logger:remove_handler(?MODULE),
+
+    File = filename:join(Dir,lists:concat([?FUNCTION_NAME,".log"])),
+    ok = logger:add_handler(?MODULE,
+                            logger_std_h,
+                            #{config => #{type => {file,File}},
+                              filter_default=>log,
+                              filters=>?DEFAULT_HANDLER_FILTERS([?MODULE]),
+                              formatter=>{?MODULE,self()}}),
+
+    {ok,#{config:=#{filesync_repeat_interval:=FSI}=FileHConfig}} =
+        logger:get_handler_config(?MODULE),
+    ok = logger:update_handler_config(?MODULE,config,
+                                      #{filesync_repeat_interval=>FSI+2000}),
+    {ok,#{config:=C5}} = logger:get_handler_config(?MODULE),
+    ct:log("C5: ~p",[C5]),
+    C5 = FileHConfig#{filesync_repeat_interval=>FSI+2000},
+
+    %% You are not allowed to actively set 'type' in runtime, since
+    %% this is a write once field.
+    {error, {illegal_config_change,_,_}} =
+        logger:set_handler_config(?MODULE,config,#{type=>standard_io}),
+    {ok,#{config:=C6}} = logger:get_handler_config(?MODULE),
+    ct:log("C6: ~p",[C6]),
+    C6 = C5,
+
+    %%  ... but if you don't specify 'type', then set_handler_config shall
+    %%  NOT reset it to its default value
+    ok = logger:set_handler_config(?MODULE,config,#{sync_mode_qlen=>1}),
+    {ok,#{config:=C7}} = logger:get_handler_config(?MODULE),
+    ct:log("C7: ~p",[C7]),
+    C7 = FileHConfig#{sync_mode_qlen=>1},
     ok.
 
 reconfig(cleanup, _Config) ->
@@ -561,8 +656,8 @@ sync(Config) ->
 
     %% check that if there's no repeated filesync active,
     %% a filesync is still performed when handler goes idle
-    logger:set_handler_config(?MODULE, config,
-                              #{filesync_repeat_interval => no_repeat}),
+    ok = logger:update_handler_config(?MODULE, config,
+                                      #{filesync_repeat_interval => no_repeat}),
     no_repeat = maps:get(filesync_repeat_interval, logger_std_h:info(?MODULE)),
     %% The following timer is to make sure the time from last log
     %% ("second") to next ("third") is long enough, so the a flush is
@@ -592,12 +687,12 @@ sync(Config) ->
     start_tracer([{logger_std_h,handle_cast,2}],
                  [OneSync || _ <- lists:seq(1, 1 + trunc(WaitT/SyncInt))]),
 
-    logger:set_handler_config(?MODULE, config,
-                              #{filesync_repeat_interval => SyncInt}),
+    ok = logger:update_handler_config(?MODULE, config,
+                                      #{filesync_repeat_interval => SyncInt}),
     SyncInt = maps:get(filesync_repeat_interval, logger_std_h:info(?MODULE)),
     timer:sleep(WaitT),
-    logger:set_handler_config(?MODULE, config,
-                              #{filesync_repeat_interval => no_repeat}),
+    ok = logger:update_handler_config(?MODULE, config,
+                                      #{filesync_repeat_interval => no_repeat}),
     check_tracer(100),
     ok.
 sync(cleanup, _Config) ->
@@ -652,7 +747,7 @@ sync_failure(Config) ->
     rpc:call(Node, ?MODULE, set_result, [file_datasync,ok]),
     
     SyncInt = 500,
-    ok = rpc:call(Node, logger, set_handler_config,
+    ok = rpc:call(Node, logger, update_handler_config,
                   [?STANDARD_HANDLER, config,
                    #{filesync_repeat_interval => SyncInt}]),
     Info = rpc:call(Node, logger_std_h, info, [?STANDARD_HANDLER]),
@@ -718,7 +813,7 @@ op_switch_to_sync_file(Config) ->
                                        drop_mode_qlen => NumOfReqs+1,
                                        flush_qlen => 2*NumOfReqs,
                                        burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     %%    TRecvPid = start_op_trace(),
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Lines = count_lines(Log),
@@ -747,7 +842,7 @@ op_switch_to_sync_tty(Config) ->
                                        drop_mode_qlen => NumOfReqs+1,
                                        flush_qlen => 2*NumOfReqs,
                                        burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     ok.
 op_switch_to_sync_tty(cleanup, _Config) ->
@@ -770,7 +865,7 @@ op_switch_to_drop_file(Config) ->
                                              flush_qlen =>
                                                  Procs*NumOfReqs*Bursts,
                                              burst_limit_enable => false}},
-                ok = logger:set_handler_config(?MODULE, NewHConfig),
+                ok = logger:update_handler_config(?MODULE, NewHConfig),
                 %% It sometimes happens that the handler gets the
                 %% requests in a slow enough pace so that dropping
                 %% never occurs. Therefore, lets generate a number of
@@ -807,7 +902,7 @@ op_switch_to_drop_tty(Config) ->
                                        flush_qlen =>
                                            Procs*NumOfReqs+1,
                                        burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     send_burst({n,NumOfReqs}, {spawn,Procs,0}, {chars,79}, notice),
     ok.
 op_switch_to_drop_tty(cleanup, _Config) ->
@@ -832,7 +927,7 @@ op_switch_to_flush_file(Config) ->
                                              drop_mode_qlen => 300,
                                              flush_qlen => 300,
                                              burst_limit_enable => false}},    
-                ok = logger:set_handler_config(?MODULE, NewHConfig),
+                ok = logger:update_handler_config(?MODULE, NewHConfig),
                 NumOfReqs = 1500,
                 Procs = 10,
                 Bursts = 10,
@@ -879,7 +974,7 @@ op_switch_to_flush_tty(Config) ->
                                        drop_mode_qlen => 100,
                                        flush_qlen => 100,
                                        burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 1000,
     Procs = 100,
     send_burst({n,NumOfReqs}, {spawn,Procs,0}, {chars,79}, notice),
@@ -895,7 +990,7 @@ limit_burst_disabled(Config) ->
                                        burst_limit_window_time => 2000,
                                        drop_mode_qlen => 200,
                                        flush_qlen => 300}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 100,
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Logged = count_lines(Log),
@@ -915,7 +1010,7 @@ limit_burst_enabled_one(Config) ->
                                        burst_limit_window_time => 2000,
                                        drop_mode_qlen => 200,
                                        flush_qlen => 300}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 100,
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Logged = count_lines(Log),
@@ -936,7 +1031,7 @@ limit_burst_enabled_period(Config) ->
                                        burst_limit_window_time => BurstTWin,
                                        drop_mode_qlen => 20000,
                                        flush_qlen => 20001}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
 
     Windows = 3,
     Sent = send_burst({t,BurstTWin*Windows}, seq, {chars,79}, notice),
@@ -956,7 +1051,7 @@ kill_disabled(Config) ->
         HConfig#{config=>StdHConfig#{overload_kill_enable=>false,
                                      overload_kill_qlen=>10,
                                      overload_kill_mem_size=>100}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     NumOfReqs = 100,
     send_burst({n,NumOfReqs}, seq, {chars,79}, notice),
     Logged = count_lines(Log),
@@ -977,7 +1072,7 @@ qlen_kill_new(Config) ->
                                      overload_kill_qlen=>10,
                                      overload_kill_mem_size=>Mem0+50000,
                                      overload_kill_restart_after=>RestartAfter}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     MRef = erlang:monitor(process, Pid0),
     NumOfReqs = 100,
     Procs = 4,
@@ -1011,7 +1106,7 @@ qlen_kill_std(_Config) ->
     %% File = lists:concat([?MODULE,"_",?FUNCTION_NAME,".log"]),
     %% Log = filename:join(Dir, File),
     %% Node = start_std_h_on_new_node(Config, ?FUNCTION_NAME, Log),
-    %% ok = rpc:call(Node, logger, set_handler_config,
+    %% ok = rpc:call(Node, logger, update_handler_config,
     %%               [?STANDARD_HANDLER, config,
     %%                #{overload_kill_enable=>true,
     %%                  overload_kill_qlen=>10,
@@ -1028,7 +1123,7 @@ mem_kill_new(Config) ->
                                      overload_kill_qlen=>50000,
                                      overload_kill_mem_size=>Mem0+500,
                                      overload_kill_restart_after=>RestartAfter}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     MRef = erlang:monitor(process, Pid0),
     NumOfReqs = 100,
     Procs = 4,
@@ -1067,7 +1162,7 @@ restart_after(Config) ->
         HConfig#{config=>StdHConfig#{overload_kill_enable=>true,
                                      overload_kill_qlen=>10,
                                      overload_kill_restart_after=>infinity}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig1),
+    ok = logger:update_handler_config(?MODULE, NewHConfig1),
     MRef1 = erlang:monitor(process, whereis(h_proc_name())),
     %% kill handler
     send_burst({n,100}, {spawn,4,0}, {chars,79}, notice),
@@ -1082,14 +1177,15 @@ restart_after(Config) ->
             ct:pal("Handler state = ~p", [Info1]),
             ct:fail("Handler not dead! It should not have survived this!")
     end,
-    
+
     {Log,_,_} = start_handler(?MODULE, ?FUNCTION_NAME, Config),
     RestartAfter = ?OVERLOAD_KILL_RESTART_AFTER,
+
     NewHConfig2 =
         HConfig#{config=>StdHConfig#{overload_kill_enable=>true,
                                      overload_kill_qlen=>10,
                                      overload_kill_restart_after=>RestartAfter}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig2),
+    ok = logger:update_handler_config(?MODULE, NewHConfig2),
     Pid0 = whereis(h_proc_name()),
     MRef2 = erlang:monitor(process, Pid0),
     %% kill handler
@@ -1123,7 +1219,7 @@ handler_requests_under_load(Config) ->
                                        drop_mode_qlen => 1000,
                                        flush_qlen => 2000,
                                        burst_limit_enable => false}},
-    ok = logger:set_handler_config(?MODULE, NewHConfig),
+    ok = logger:update_handler_config(?MODULE, NewHConfig),
     Pid = spawn_link(fun() -> send_requests(?MODULE, 1, [{filesync,[]},
                                                          {info,[]},
                                                          {reset,[]},
@@ -1155,9 +1251,9 @@ send_requests(HName, TO, Reqs = [{Req,Res}|Rs]) ->
             Result =
                 case Req of
                     change_config ->
-                        logger:set_handler_config(HName, config,
-                                                  #{overload_kill_enable =>
-                                                        false});
+                        logger:update_handler_config(HName, config,
+                                                     #{overload_kill_enable =>
+                                                           false});
                     Func ->
                         logger_std_h:Func(HName)
                 end,