diff --git a/src/emqx_session.erl b/src/emqx_session.erl
index 8612d9f16..0364bde61 100644
--- a/src/emqx_session.erl
+++ b/src/emqx_session.erl
@@ -165,6 +165,7 @@
 
 -ifdef(TEST).
 -define(GET_CLIENT_ID(C), maps:get(clientid, C, <<>>)).
+-export([dummy/0]).
 -else.
 -define(GET_CLIENT_ID(C), maps:get(clientid, C)).
 -endif.
@@ -200,14 +201,20 @@ init_mqueue(Zone) ->
 
 %% @doc uprade from 4.3
 upgrade(CInfo, S) ->
+    ?LOG(warning, "upgrading from 4.3", []),
     [session | Fields] = tuple_to_list(S),
     #session{} = list_to_tuple([session, ?GET_CLIENT_ID(CInfo) | Fields] ++ [#{}]).
 
 %% @doc Downgrade to 4.3
 downgrade(#session{} = S) ->
+    ?LOG(warning, "downgrading to 4.3", []),
     [session, _ClientID | Fields] = tuple_to_list(S),
     list_to_tuple([session | lists:reverse(tl(lists:reverse(Fields)))]).
 
+-ifdef(TEST).
+dummy() ->
+    #session{}.
+-endif.
 %%--------------------------------------------------------------------
 %% Info, Stats
 %%--------------------------------------------------------------------
diff --git a/test/emqx_cm_SUITE.erl b/test/emqx_cm_SUITE.erl
index 4fcaaf473..84b362c0a 100644
--- a/test/emqx_cm_SUITE.erl
+++ b/test/emqx_cm_SUITE.erl
@@ -332,15 +332,17 @@ t_discard_session_race(_) ->
 t_takeover_session(_) ->
     #{conninfo := ConnInfo} = ?ChanInfo,
     {error, not_found} = emqx_cm:takeover_session(<<"clientid">>),
+    Dummy = emqx_session:dummy(),
+    Downgraded = emqx_session:downgrade(Dummy),
     erlang:spawn_link(fun() ->
         ok = emqx_cm:register_channel(<<"clientid">>, self(), ConnInfo),
         receive
             {'$gen_call', From, {takeover, 'begin'}} ->
-                gen_server:reply(From, test), ok
+                gen_server:reply(From, Dummy), ok
         end
     end),
     timer:sleep(100),
-    {ok, emqx_connection, _, test} = emqx_cm:takeover_session(<<"clientid">>),
+    {ok, emqx_connection, _, Downgraded} = emqx_cm:takeover_session(<<"clientid">>),
     emqx_cm:unregister_channel(<<"clientid">>).
 
 t_all_channels(_) ->