diff --git a/.github/actions/package-macos/action.yaml b/.github/actions/package-macos/action.yaml
index 7e9a3cf9d..99b225576 100644
--- a/.github/actions/package-macos/action.yaml
+++ b/.github/actions/package-macos/action.yaml
@@ -55,10 +55,18 @@ runs:
         fi
         git clone --depth 1 --branch OTP-${{ inputs.otp }} https://github.com/emqx/otp.git "$OTP_SOURCE_PATH"
         cd "$OTP_SOURCE_PATH"
+        if [ "$(arch)" = arm64 ]; then
+            export LDFLAGS="-L$(brew --prefix unixodbc)/lib"
+            export CC="/usr/bin/gcc -I$(brew --prefix unixodbc)/include"
+        fi
         ./configure --disable-dynamic-ssl-lib --with-ssl=$(brew --prefix openssl@1.1) --disable-hipe --disable-jit --prefix="$OTP_INSTALL_PATH"
         make -j$(nproc)
         rm -rf "$OTP_INSTALL_PATH"
         make install
+        if [ "$(arch)" = arm64 ]; then
+            unset LDFLAGS
+            unset CC
+        fi
     - name: build
       env:
         HOMEBREW_NO_AUTO_UPDATE: 1
diff --git a/apps/emqx_exhook/src/emqx_exhook.app.src b/apps/emqx_exhook/src/emqx_exhook.app.src
index edf1701be..839d83b96 100644
--- a/apps/emqx_exhook/src/emqx_exhook.app.src
+++ b/apps/emqx_exhook/src/emqx_exhook.app.src
@@ -1,7 +1,7 @@
 %% -*- mode: erlang -*-
 {application, emqx_exhook,
  [{description, "EMQ X Extension for Hook"},
-  {vsn, "4.4.5"},
+  {vsn, "4.4.6"},
   {modules, []},
   {registered, []},
   {mod, {emqx_exhook_app, []}},
diff --git a/apps/emqx_exhook/src/emqx_exhook.appup.src b/apps/emqx_exhook/src/emqx_exhook.appup.src
index cc9ca9af7..b0be62eb5 100644
--- a/apps/emqx_exhook/src/emqx_exhook.appup.src
+++ b/apps/emqx_exhook/src/emqx_exhook.appup.src
@@ -1,7 +1,8 @@
 %% -*- mode: erlang -*-
 %% Unless you know what you are doing, DO NOT edit manually!!
 {VSN,
-  [{"4.4.4",
+  [{"4.4.5",[{load_module,emqx_exhook_pb,brutal_purge,soft_purge,[]}]},
+   {"4.4.4",
     [{load_module,emqx_exhook_handler,brutal_purge,soft_purge,[]},
      {load_module,emqx_exhook_pb,brutal_purge,soft_purge,[]}]},
    {"4.4.3",
@@ -22,7 +23,8 @@
      {load_module,emqx_exhook_handler,brutal_purge,soft_purge,[]},
      {update,emqx_exhook_mngr,{advanced,["4.4.0"]}}]},
    {<<".*">>,[]}],
-  [{"4.4.4",
+  [{"4.4.5",[{load_module,emqx_exhook_pb,brutal_purge,soft_purge,[]}]},
+   {"4.4.4",
     [{load_module,emqx_exhook_handler,brutal_purge,soft_purge,[]},
      {load_module,emqx_exhook_pb,brutal_purge,soft_purge,[]}]},
    {"4.4.3",
diff --git a/apps/emqx_rule_engine/src/emqx_rule_engine.app.src b/apps/emqx_rule_engine/src/emqx_rule_engine.app.src
index 9996a2e46..8c1feb42f 100644
--- a/apps/emqx_rule_engine/src/emqx_rule_engine.app.src
+++ b/apps/emqx_rule_engine/src/emqx_rule_engine.app.src
@@ -1,6 +1,6 @@
 {application, emqx_rule_engine,
  [{description, "EMQ X Rule Engine"},
-  {vsn, "4.4.12"}, % strict semver, bump manually!
+  {vsn, "4.4.13"}, % strict semver, bump manually!
   {modules, []},
   {registered, [emqx_rule_engine_sup, emqx_rule_registry, emqx_rule_engine_jwt_sup]},
   {applications, [kernel,stdlib,rulesql,getopt,jose]},
diff --git a/apps/emqx_rule_engine/src/emqx_rule_engine.appup.src b/apps/emqx_rule_engine/src/emqx_rule_engine.appup.src
index 4b392eb01..c3273d701 100644
--- a/apps/emqx_rule_engine/src/emqx_rule_engine.appup.src
+++ b/apps/emqx_rule_engine/src/emqx_rule_engine.appup.src
@@ -1,13 +1,13 @@
 %% -*- mode: erlang -*-
 %% Unless you know what you are doing, DO NOT edit manually!!
 {VSN,
-  [{"4.4.11",[
-    {load_module,emqx_rule_registry,brutal_purge,soft_purge,[]},
-    {load_module,emqx_rule_engine_sup,brutal_purge,soft_purge,[]},
-    {load_module,emqx_rule_engine_api,brutal_purge,soft_purge,[]},
-    {apply,{emqx_rule_engine_sup,ensure_api_delegator_started,[]}},
-    {load_module,emqx_rule_engine,brutal_purge,soft_purge,[]}
-   ]},
+  [{"4.4.12",[{load_module,emqx_rule_registry,brutal_purge,soft_purge,[]}]},
+   {"4.4.11",
+    [{load_module,emqx_rule_registry,brutal_purge,soft_purge,[]},
+     {load_module,emqx_rule_engine_sup,brutal_purge,soft_purge,[]},
+     {load_module,emqx_rule_engine_api,brutal_purge,soft_purge,[]},
+     {apply,{emqx_rule_engine_sup,ensure_api_delegator_started,[]}},
+     {load_module,emqx_rule_engine,brutal_purge,soft_purge,[]}]},
    {"4.4.10",
     [{add_module,emqx_rule_engine_jwt},
      {add_module,emqx_rule_engine_jwt_worker},
@@ -213,13 +213,13 @@
      {load_module,emqx_rule_engine,brutal_purge,soft_purge,[]},
      {load_module,emqx_rule_runtime,brutal_purge,soft_purge,[]}]},
    {<<".*">>,[]}],
-  [{"4.4.11",[
-    {load_module,emqx_rule_registry,brutal_purge,soft_purge,[]},
-    {apply,{emqx_rule_engine_sup,ensure_api_delegator_stopped,[]}},
-    {load_module,emqx_rule_engine_sup,brutal_purge,soft_purge,[]},
-    {load_module,emqx_rule_engine_api,brutal_purge,soft_purge,[]},
-    {load_module,emqx_rule_engine,brutal_purge,soft_purge,[]}
-   ]},
+  [{"4.4.12",[{load_module,emqx_rule_registry,brutal_purge,soft_purge,[]}]},
+   {"4.4.11",
+    [{load_module,emqx_rule_registry,brutal_purge,soft_purge,[]},
+     {apply,{emqx_rule_engine_sup,ensure_api_delegator_stopped,[]}},
+     {load_module,emqx_rule_engine_sup,brutal_purge,soft_purge,[]},
+     {load_module,emqx_rule_engine_api,brutal_purge,soft_purge,[]},
+     {load_module,emqx_rule_engine,brutal_purge,soft_purge,[]}]},
    {"4.4.10",
     [{load_module,emqx_rule_actions,brutal_purge,soft_purge,[]},
      {apply,{emqx_rule_engine_sup,ensure_api_delegator_stopped,[]}},
diff --git a/apps/emqx_rule_engine/src/emqx_rule_engine.erl b/apps/emqx_rule_engine/src/emqx_rule_engine.erl
index f3e1651d4..6e8f00329 100644
--- a/apps/emqx_rule_engine/src/emqx_rule_engine.erl
+++ b/apps/emqx_rule_engine/src/emqx_rule_engine.erl
@@ -698,6 +698,7 @@ init_resource(Module, OnCreate, ResId, Config) ->
     ResParams = #resource_params{id = ResId,
                                  params = Params,
                                  status = #{is_alive => true}},
+    maybe_resource_down(ResId, clear),
     emqx_rule_registry:add_resource_params(ResParams).
 
 init_resource_with_retrier(Module, OnCreate, ResId, Config) ->
@@ -706,6 +707,7 @@ init_resource_with_retrier(Module, OnCreate, ResId, Config) ->
     ResParams = #resource_params{id = ResId,
                                  params = Params,
                                  status = #{is_alive => true}},
+    maybe_resource_down(ResId, clear),
     emqx_rule_registry:add_resource_params(ResParams).
 
 init_action(Module, OnCreate, ActionInstId, Params) ->
@@ -726,12 +728,10 @@ init_action(Module, OnCreate, ActionInstId, Params) ->
     end.
 
 clear_resource(_Module, undefined, ResId, Type) ->
-    Name = alarm_name_of_resource_down(Type, ResId),
-    _ = emqx_alarm:deactivate(Name),
+    clear_resource_down(ResId, Type),
     ok = emqx_rule_registry:remove_resource_params(ResId);
 clear_resource(Module, Destroy, ResId, Type) ->
-    Name = alarm_name_of_resource_down(Type, ResId),
-    _ = emqx_alarm:deactivate(Name),
+    clear_resource_down(ResId, Type),
     case emqx_rule_registry:find_resource_params(ResId) of
         {ok, #resource_params{params = Params}} ->
             ?RAISE(Module:Destroy(ResId, Params),
@@ -779,14 +779,10 @@ fetch_resource_status(Module, OnStatus, ResId) ->
                 case Module:OnStatus(ResId, Params) of
                     #{is_alive := LastIsAlive} = Status -> Status;
                     #{is_alive := true} = Status ->
-                        {ok, Type} = find_type(ResId),
-                        Name = alarm_name_of_resource_down(Type, ResId),
-                        emqx_alarm:deactivate(Name),
+                        maybe_resource_down(ResId, clear),
                         Status;
                     #{is_alive := false} = Status ->
-                        {ok, Type} = find_type(ResId),
-                        Name = alarm_name_of_resource_down(Type, ResId),
-                        emqx_alarm:activate(Name, #{id => ResId, type => Type}),
+                        maybe_resource_down(ResId, alarm),
                         Status
                 end
             catch _Error:Reason:STrace ->
@@ -824,9 +820,23 @@ refresh_actions(Actions, Pred) ->
             end
         end, Actions).
 
-find_type(ResId) ->
-    {ok, #resource{type = Type}} = emqx_rule_registry:find_resource(ResId),
-    {ok, Type}.
+maybe_resource_down(ResId, AlarmOrClear) ->
+    case emqx_rule_registry:find_resource(ResId) of
+        {ok, #resource{type = Type}} ->
+            _ = case AlarmOrClear of
+                alarm -> alarm_resource_down(ResId, Type);
+                clear -> clear_resource_down(ResId, Type)
+            end,
+            ok;
+        not_found ->
+            ok
+    end.
+
+alarm_resource_down(ResId, Type) ->
+    emqx_alarm:activate(alarm_name_of_resource_down(Type, ResId),
+        #{id => ResId, type => Type}).
+clear_resource_down(ResId, Type) ->
+    emqx_alarm:deactivate(alarm_name_of_resource_down(Type, ResId)).
 
 alarm_name_of_resource_down(Type, ResId) ->
     unicode:characters_to_binary(io_lib:format("resource/~ts/~ts/down", [Type, ResId])).
diff --git a/apps/emqx_rule_engine/test/emqx_rule_monitor_SUITE.erl b/apps/emqx_rule_engine/test/emqx_rule_monitor_SUITE.erl
index fac76d235..b3a44ff34 100644
--- a/apps/emqx_rule_engine/test/emqx_rule_monitor_SUITE.erl
+++ b/apps/emqx_rule_engine/test/emqx_rule_monitor_SUITE.erl
@@ -89,13 +89,17 @@ end_per_testcase(_, Config) ->
     Config.
 
 common_init_per_testcase() ->
+    AlarmOpts = [{actions, [log, publish]}, {size_limit, 1000}, {validity_period, 86400}],
+    {ok, _} = emqx_alarm:start_link(AlarmOpts),
     {ok, _} = emqx_rule_monitor:start_link().
 
 common_end_per_testcases() ->
+    ok = emqx_alarm:stop(),
     emqx_rule_monitor:erase_retry_interval(),
     emqx_rule_monitor:stop().
 
 t_restart_resource(_) ->
+    ct:pal("emqx_alarm: ~p", [sys:get_state(whereis(emqx_alarm))]),
     ok = emqx_rule_registry:register_resource_types(
             [#resource_type{
                 name = test_res_1,
diff --git a/apps/emqx_rule_engine/test/emqx_rule_utils_SUITE.erl b/apps/emqx_rule_engine/test/emqx_rule_utils_SUITE.erl
index ae3f72254..c924b1d71 100644
--- a/apps/emqx_rule_engine/test/emqx_rule_utils_SUITE.erl
+++ b/apps/emqx_rule_engine/test/emqx_rule_utils_SUITE.erl
@@ -21,7 +21,7 @@
 
 -include_lib("eunit/include/eunit.hrl").
 
--define(PORT, 9876).
+-define(PORT, 29876).
 
 all() -> emqx_ct:all(?MODULE).
 
diff --git a/build b/build
index d3c9164eb..9cc68e531 100755
--- a/build
+++ b/build
@@ -69,6 +69,8 @@ make_rel() {
 
 relup_db() {
     case "$PROFILE" in
+        *edge*)
+            ;;
         *-ee*)
             ./scripts/relup-base-vsns.escript "$@" ./data/relup-paths-ee.eterm
             ;;
diff --git a/changes/v4.4.12-en.md b/changes/v4.4.12-en.md
index 3df067609..0c1e02ce2 100644
--- a/changes/v4.4.12-en.md
+++ b/changes/v4.4.12-en.md
@@ -25,3 +25,14 @@
 - Fixed EMQX Helm Chart can not set JSON type value for EMQX Broker configuration items [#9504](https://github.com/emqx/emqx/pull/9504).
 
 - When resource creation is too slow, there may be some temporary probing connections left [#9539](https://github.com/emqx/emqx/pull/9539).
+
+- After a reconnect, the unacknowledged QoS1/QoS2 messages in non-clean session were not retransmitted periodically as before the reconnect [#9627](https://github.com/emqx/emqx/pull/9627).
+  The configuration `zone.<zone-name>.retry_interval` specifies the retransmission interval of
+  unacknowledged QoS1/QoS2 messages (defaults to 30s).
+  Prior to this fix, unacknowledged messages buffered in the session are re-sent only once after session take-over, but not retried at configured interval.
+
+- The expired 'awaiting_rel' queue is not cleared after persistent session MQTT client disconnected [#9627](https://github.com/emqx/emqx/pull/9627).
+  Before this change, if the 'awaiting_rel' queue is full when the MQTT client reconnect
+  to the broker and publish a QoS2 message, the client will get disconnected by the broker
+  with reason code RC_RECEIVE_MAXIMUM_EXCEEDED(0x93), even if the packet IDs in the 'awaiting_rel'
+  queue have already expired.
diff --git a/changes/v4.4.12-zh.md b/changes/v4.4.12-zh.md
index d986aca93..89463faef 100644
--- a/changes/v4.4.12-zh.md
+++ b/changes/v4.4.12-zh.md
@@ -26,3 +26,11 @@
 - 修复 EMQX Helm Chart 无法配置 value 为 JSON 类型的 EMQX Broker 配置项 [#9504](https://github.com/emqx/emqx/pull/9504)。
 
 - 当创建资源过慢的情况下，有可能会残留一些用来探活的临时的连接 [#9539](https://github.com/emqx/emqx/pull/9539)。
+
+- 持久会话的 MQTT 客户端重新连接 emqx 之后，未被确认过的 QoS1/QoS2 消息不再周期性重发 [#9627](https://github.com/emqx/emqx/pull/9627)。
+  `zone.<zone-name>.retry_interval` 配置指定了没有被确认过的 QoS1/QoS2 消息的重发间隔，(默认为 30s)。在这个修复之前，
+  当持久会话的 MQTT 客户端重新连接 emqx 之后，emqx 会将队列中缓存的未被确认过的消息重发一次，但是不会按配置的时间间隔重试。
+
+- 持久会话的 MQTT 客户端断连之后，已经过期的 'awaiting_rel' 队列没有清除 [#9627](https://github.com/emqx/emqx/pull/9627)。
+  在这个改动之前，在客户端重连并且发布 QoS2 消息的时候，如果 'awaiting_rel' 队列已满，此客户端会被服务器以
+  RC_RECEIVE_MAXIMUM_EXCEEDED(0x93) 错误码断开连接，即使这时候 'awaiting_rel' 队列里面的报文 ID 已经过期了。
diff --git a/data/relup-paths.eterm b/data/relup-paths.eterm
index a1f7e912c..e03f4d839 100644
--- a/data/relup-paths.eterm
+++ b/data/relup-paths.eterm
@@ -51,6 +51,12 @@
         <<"4.4.5">>,<<"4.4.6">>,<<"4.4.7">>,<<"4.4.8">>,<<"4.4.9">>,
         <<"4.4.10">>,<<"4.4.11">>],
    otp => <<"24.3.4.2-1">>}}.
+{<<"4.4.13">>,
+ #{from_versions =>
+       [<<"4.4.0">>,<<"4.4.1">>,<<"4.4.2">>,<<"4.4.3">>,<<"4.4.4">>,
+        <<"4.4.5">>,<<"4.4.6">>,<<"4.4.7">>,<<"4.4.8">>,<<"4.4.9">>,
+        <<"4.4.10">>,<<"4.4.11">>,<<"4.4.12">>],
+   otp => <<"24.3.4.2-1">>}}.
 {<<"4.5.0">>,
  #{from_versions => [<<"4.4.8">>,<<"4.4.9">>,<<"4.4.10">>,
                      <<"4.4.11">>],
diff --git a/deploy/charts/emqx/Chart.yaml b/deploy/charts/emqx/Chart.yaml
index a4f2e1a6d..523793eef 100644
--- a/deploy/charts/emqx/Chart.yaml
+++ b/deploy/charts/emqx/Chart.yaml
@@ -13,8 +13,8 @@ type: application
 
 # This is the chart version. This version number should be incremented each time you make changes
 # to the chart and its templates, including the app version.
-version: 4.4.12
+version: 4.4.13
 
 # This is the version number of the application being deployed. This version number should be
 # incremented each time you make changes to the application.
-appVersion: 4.4.12
+appVersion: 4.4.13
diff --git a/include/emqx_release.hrl b/include/emqx_release.hrl
index 929adf705..250c76e71 100644
--- a/include/emqx_release.hrl
+++ b/include/emqx_release.hrl
@@ -29,7 +29,7 @@
 
 -ifndef(EMQX_ENTERPRISE).
 
--define(EMQX_RELEASE, {opensource, "4.4.12-alpha.2"}).
+-define(EMQX_RELEASE, {opensource, "4.4.13-alpha.1"}).
 
 -else.
 
diff --git a/lib-ce/emqx_dashboard/src/emqx_dashboard.app.src b/lib-ce/emqx_dashboard/src/emqx_dashboard.app.src
index c9c273344..38a5ee5a2 100644
--- a/lib-ce/emqx_dashboard/src/emqx_dashboard.app.src
+++ b/lib-ce/emqx_dashboard/src/emqx_dashboard.app.src
@@ -1,6 +1,6 @@
 {application, emqx_dashboard,
  [{description, "EMQX Web Dashboard"},
-  {vsn, "4.4.11"}, % strict semver, bump manually!
+  {vsn, "4.4.12"}, % strict semver, bump manually!
   {modules, []},
   {registered, [emqx_dashboard_sup]},
   {applications, [kernel,stdlib,mnesia,minirest]},
diff --git a/rebar.config b/rebar.config
index 64e9f2dec..fbb49ce9d 100644
--- a/rebar.config
+++ b/rebar.config
@@ -60,9 +60,9 @@
     , {recon, {git, "https://github.com/ferd/recon", {tag, "2.5.1"}}}
     , {observer_cli, "1.6.1"} % NOTE: depends on recon 2.5.1
     , {getopt, "1.0.1"}
-    , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "1.0.1"}}}
+    , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "1.0.3"}}}
     , {lc, {git, "https://github.com/emqx/lc.git", {tag, "0.3.2"}}}
-    , {mongodb, {git,"https://github.com/emqx/mongodb-erlang", {tag, "v3.0.15"}}}
+    , {mongodb, {git,"https://github.com/emqx/mongodb-erlang", {tag, "v3.0.17"}}}
     , {epgsql, {git, "https://github.com/emqx/epgsql.git", {tag, "4.6.0"}}}
     , {grpc, {git, "https://github.com/emqx/grpc-erl", {tag, "0.6.7"}}}
     ]}.
diff --git a/scripts/macos-sign-binaries.sh b/scripts/macos-sign-binaries.sh
index 135730694..b41c8088d 100755
--- a/scripts/macos-sign-binaries.sh
+++ b/scripts/macos-sign-binaries.sh
@@ -21,9 +21,16 @@ REL_DIR="${1}"
 PKSC12_FILE="$HOME/developer-id-application.p12"
 base64 --decode > "${PKSC12_FILE}" <<<"${APPLE_DEVELOPER_ID_BUNDLE}"
 
-KEYCHAIN='emqx.keychain-db'
+KEYCHAIN="emqx-$(date +%s).keychain-db"
 KEYCHAIN_PASSWORD="$(openssl rand -base64 32)"
 
+trap cleanup EXIT
+
+function cleanup {
+    set +e
+    security delete-keychain "${KEYCHAIN}" 2>/dev/null
+}
+
 security create-keychain -p "${KEYCHAIN_PASSWORD}" "${KEYCHAIN}"
 security set-keychain-settings -lut 21600 "${KEYCHAIN}"
 security unlock-keychain -p "${KEYCHAIN_PASSWORD}" "${KEYCHAIN}"
@@ -64,3 +71,5 @@ for f in \
     ; do
     find "${REL_DIR}"/lib/ -name "$f" -exec codesign -s "${APPLE_DEVELOPER_IDENTITY}" -f --verbose=4 --timestamp --options=runtime {} \;
 done
+
+cleanup
diff --git a/scripts/relup-base-vsns.sh b/scripts/relup-base-vsns.sh
index 1aa2b3288..ba19c7d05 100755
--- a/scripts/relup-base-vsns.sh
+++ b/scripts/relup-base-vsns.sh
@@ -46,6 +46,10 @@ case "${EDITION}" in
         GIT_TAG_PREFIX="e"
         RELUP_PATH_FILE="./data/relup-paths-ee.eterm"
         ;;
+    *edge*)
+        # no relup for emqx-edge
+        exit 0
+        ;;
     *)
         GIT_TAG_PREFIX="v"
         RELUP_PATH_FILE="./data/relup-paths.eterm"
diff --git a/src/emqx.app.src b/src/emqx.app.src
index 47b9cd084..6d9aeb76f 100644
--- a/src/emqx.app.src
+++ b/src/emqx.app.src
@@ -6,7 +6,7 @@
   %% the emqx `release' version, which in turn is comprised of several
   %% apps, one of which is this.  See `emqx_release.hrl' for more
   %% info.
-  {vsn, "4.4.12"}, % strict semver, bump manually!
+  {vsn, "4.4.13"}, % strict semver, bump manually!
   {modules, []},
   {registered, []},
   {applications, [ kernel
diff --git a/src/emqx.appup.src b/src/emqx.appup.src
index b41e751d6..4aada41b8 100644
--- a/src/emqx.appup.src
+++ b/src/emqx.appup.src
@@ -1,7 +1,12 @@
 %% -*- mode: erlang -*-
 %% Unless you know what you are doing, DO NOT edit manually!!
 {VSN,
-  [{"4.4.11",
+  [{"4.4.12",
+    [{load_module,emqx_cm,brutal_purge,soft_purge,[]},
+     {load_module,emqx_misc,brutal_purge,soft_purge,[]},
+     {load_module,emqx_relup,brutal_purge,soft_purge,[]},
+     {load_module,emqx_app,brutal_purge,soft_purge,[]}]},
+   {"4.4.11",
     [{add_module,emqx_cover},
      {load_module,emqx_relup,brutal_purge,soft_purge,[]},
      {load_module,emqx_misc,brutal_purge,soft_purge,[]},
@@ -27,7 +32,8 @@
      {load_module,emqx_cm,brutal_purge,soft_purge,[]},
      {load_module,emqx,brutal_purge,soft_purge,[]},
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.9",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -52,7 +58,8 @@
      {load_module,emqx_connection,brutal_purge,soft_purge,[]},
      {load_module,emqx_router,brutal_purge,soft_purge,[]},
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.8",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -78,7 +85,8 @@
      {load_module,emqx_shared_sub,brutal_purge,soft_purge,[]},
      {load_module,emqx_cm,brutal_purge,soft_purge,[]},
      {load_module,emqx_message,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.7",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -104,7 +112,8 @@
      {load_module,emqx_plugins,brutal_purge,soft_purge,[]},
      {load_module,emqx_channel,brutal_purge,soft_purge,[]},
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.6",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -130,7 +139,8 @@
      {load_module,emqx_plugins,brutal_purge,soft_purge,[]},
      {load_module,emqx_channel,brutal_purge,soft_purge,[]},
      {load_module,emqx,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.5",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -158,7 +168,8 @@
      {load_module,emqx_plugins,brutal_purge,soft_purge,[]},
      {load_module,emqx_channel,brutal_purge,soft_purge,[]},
      {load_module,emqx_session,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.4",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -193,7 +204,8 @@
      {load_module,emqx_plugins,brutal_purge,soft_purge,[]},
      {load_module,emqx_metrics,brutal_purge,soft_purge,[]},
      {load_module,emqx_session,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.3",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -235,7 +247,8 @@
      {load_module,emqx_access_control,brutal_purge,soft_purge,[]},
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
      {load_module,emqx_relup},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.2",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -278,7 +291,8 @@
      {load_module,emqx_hooks,brutal_purge,soft_purge,[]},
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
      {load_module,emqx_relup},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.1",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -326,7 +340,8 @@
      {load_module,emqx_misc,brutal_purge,soft_purge,[]},
      {load_module,emqx_connection,brutal_purge,soft_purge,[]},
      {add_module,emqx_relup},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {"4.4.0",
     [{add_module,emqx_cover},
      {add_module,emqx_ocsp_cache},
@@ -376,9 +391,15 @@
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
      {load_module,emqx_message,brutal_purge,soft_purge,[]},
      {load_module,emqx_limiter,brutal_purge,soft_purge,[]},
-     {apply, {application, set_env, [gen_rpc, insecure_auth_fallback_allowed, true]}}]},
+     {apply,{application,set_env,
+                         [gen_rpc,insecure_auth_fallback_allowed,true]}}]},
    {<<".*">>,[]}],
-  [{"4.4.11",
+  [{"4.4.12",
+    [{load_module,emqx_cm,brutal_purge,soft_purge,[]},
+     {load_module,emqx_misc,brutal_purge,soft_purge,[]},
+     {load_module,emqx_relup,brutal_purge,soft_purge,[]},
+     {load_module,emqx_app,brutal_purge,soft_purge,[]}]},
+   {"4.4.11",
     [{load_module,emqx_relup,brutal_purge,soft_purge,[]},
      {load_module,emqx_app,brutal_purge,soft_purge,[]},
      {load_module,emqx_misc,brutal_purge,soft_purge,[]},
diff --git a/src/emqx_channel.erl b/src/emqx_channel.erl
index 791433b37..daaec16e1 100644
--- a/src/emqx_channel.erl
+++ b/src/emqx_channel.erl
@@ -56,9 +56,12 @@
         , clear_keepalive/1
         ]).
 
-%% Exports for CT
 -export([set_field/3]).
 
+-ifdef(TEST).
+-export([ensure_timer/3]).
+-endif.
+
 -import(emqx_misc,
         [ run_fold/3
         , pipeline/3
@@ -622,20 +625,20 @@ do_publish(PacketId, Msg = #message{qos = ?QOS_1}, Channel) ->
     NChannel = ensure_quota(PubRes, Channel),
     handle_out(puback, {PacketId, RC}, NChannel);
 
-do_publish(PacketId, Msg = #message{qos = ?QOS_2},
-           Channel = #channel{session = Session}) ->
+do_publish(PacketId, Msg = #message{qos = ?QOS_2}, Channel0) ->
+    #channel{session = Session} = NChannel = maybe_clean_expired_awaiting_rel(Channel0),
     case emqx_session:publish(PacketId, Msg, Session) of
         {ok, PubRes, NSession} ->
             RC = puback_reason_code(PubRes),
-            NChannel1 = ensure_timer(await_timer, Channel#channel{session = NSession}),
+            NChannel1 = ensure_timer(await_timer, NChannel#channel{session = NSession}),
             NChannel2 = ensure_quota(PubRes, NChannel1),
             handle_out(pubrec, {PacketId, RC}, NChannel2);
         {error, RC = ?RC_PACKET_IDENTIFIER_IN_USE} ->
             ok = emqx_metrics:inc('packets.publish.inuse'),
-            handle_out(pubrec, {PacketId, RC}, Channel);
+            handle_out(pubrec, {PacketId, RC}, NChannel);
         {error, RC = ?RC_RECEIVE_MAXIMUM_EXCEEDED} ->
             ok = emqx_metrics:inc('packets.publish.dropped'),
-            handle_out(disconnect, RC, Channel)
+            handle_out(disconnect, RC, NChannel)
     end.
 
 ensure_quota(_, Channel = #channel{quota = undefined}) ->
@@ -841,7 +844,6 @@ handle_out(connack, {?RC_SUCCESS, SP, Props}, Channel = #channel{conninfo = Conn
                           [ConnInfo, emqx_reason_codes:name(?RC_SUCCESS)],
                           AckProps
                          ),
-
     return_connack(?CONNACK_PACKET(?RC_SUCCESS, SP, NAckProps),
                    ensure_keepalive(NAckProps, Channel));
 
@@ -923,7 +925,7 @@ return_connack(AckPacket, Channel) ->
                                       },
             {Packets, NChannel1} = do_deliver(Publishes, NChannel),
             Outgoing = [{outgoing, Packets} || length(Packets) > 0],
-            {ok, Replies ++ Outgoing, NChannel1}
+            {ok, Replies ++ Outgoing, ensure_timer(retry_timer, NChannel1)}
     end.
 
 %%--------------------------------------------------------------------
@@ -1127,17 +1129,8 @@ handle_timeout(_TRef, retry_delivery,
             handle_out(publish, Publishes, reset_timer(retry_timer, Timeout, NChannel))
     end;
 
-handle_timeout(_TRef, expire_awaiting_rel,
-               Channel = #channel{conn_state = disconnected}) ->
-    {ok, Channel};
-handle_timeout(_TRef, expire_awaiting_rel,
-               Channel = #channel{session = Session}) ->
-    case emqx_session:expire(awaiting_rel, Session) of
-        {ok, NSession} ->
-            {ok, clean_timer(await_timer, Channel#channel{session = NSession})};
-        {ok, Timeout, NSession} ->
-            {ok, reset_timer(await_timer, Timeout, Channel#channel{session = NSession})}
-    end;
+handle_timeout(_TRef, expire_awaiting_rel, Channel) ->
+    {ok, clean_expired_awaiting_rel(Channel)};
 
 handle_timeout(_TRef, expire_session, Channel) ->
     shutdown(expired, Channel);
@@ -1182,6 +1175,26 @@ reset_timer(Name, Time, Channel) ->
 clean_timer(Name, Channel = #channel{timers = Timers}) ->
     Channel#channel{timers = maps:remove(Name, Timers)}.
 
+is_timer_alive(Name, #channel{timers = Timers}) ->
+    case maps:find(Name, Timers) of
+        error -> false;
+        {ok, _TRef} -> true
+    end.
+
+maybe_clean_expired_awaiting_rel(Channel) ->
+    case is_timer_alive(await_timer, Channel) of
+        true -> Channel;
+        false -> clean_expired_awaiting_rel(Channel)
+    end.
+
+clean_expired_awaiting_rel(Channel = #channel{session = Session}) ->
+    case emqx_session:expire(awaiting_rel, Session) of
+        {ok, NSession} ->
+            clean_timer(await_timer, Channel#channel{session = NSession});
+        {ok, Timeout, NSession} ->
+            reset_timer(await_timer, Timeout, Channel#channel{session = NSession})
+    end.
+
 -spec interval(channel_timer(), channel()) -> timeout().
 interval(alive_timer, #channel{keepalive = KeepAlive}) ->
     emqx_keepalive:info(interval, KeepAlive);
@@ -1878,10 +1891,6 @@ is_disconnect_event_enabled(discarded) ->
 is_disconnect_event_enabled(takeovered) ->
     emqx:get_env(client_disconnect_takeovered, false).
 
-%%--------------------------------------------------------------------
-%% For CT tests
-%%--------------------------------------------------------------------
-
 set_field(Name, Value, Channel) ->
     Pos = emqx_misc:index_of(Name, record_info(fields, channel)),
     setelement(Pos+1, Channel, Value).
diff --git a/src/emqx_cm.erl b/src/emqx_cm.erl
index f40e803e8..7983c0be5 100644
--- a/src/emqx_cm.erl
+++ b/src/emqx_cm.erl
@@ -558,7 +558,8 @@ code_change(_OldVsn, State, _Extra) ->
 %%--------------------------------------------------------------------
 
 clean_down({ChanPid, ClientId}) ->
-    do_unregister_channel({ClientId, ChanPid}).
+    do_unregister_channel({ClientId, ChanPid}),
+    ?tp(debug, emqx_cm_clean_down, #{client_id => ClientId}).
 
 stats_fun() ->
     lists:foreach(fun update_stats/1, ?CHAN_STATS).
diff --git a/src/emqx_relup.erl b/src/emqx_relup.erl
index 182a60c7b..a85079753 100644
--- a/src/emqx_relup.erl
+++ b/src/emqx_relup.erl
@@ -31,12 +31,14 @@
 post_release_upgrade(FromRelVsn, _) ->
     {_, CurrRelVsn} = ?EMQX_RELEASE,
     ?INFO("emqx has been upgraded from ~s to ~s!", [FromRelVsn, CurrRelVsn]),
+    maybe_refresh_jwt_module(FromRelVsn),
     reload_components().
 
 %% What to do after downgraded to an old release vsn.
 post_release_downgrade(ToRelVsn, _) ->
     {_, CurrRelVsn} = ?EMQX_RELEASE,
     ?INFO("emqx has been downgraded from ~s to ~s!", [CurrRelVsn, ToRelVsn]),
+    maybe_refresh_jwt_module(ToRelVsn),
     reload_components().
 
 -ifdef(EMQX_ENTERPRISE).
@@ -73,3 +75,21 @@ load_plugins() ->
         true -> emqx_plugins:force_load();
         false -> emqx_plugins:load()
     end.
+
+-ifdef(EMQX_ENTERPRISE).
+maybe_refresh_jwt_module(Release) when Release =:= "4.4.0"
+    orelse Release =:= "4.4.1"
+    orelse Release =:= "4.4.2"
+    orelse Release =:= "4.4.3" ->
+    _ = emqx:unhook('client.authenticate', fun emqx_auth_jwt:check/3),
+    _ = emqx:unhook('client.authenticate', fun emqx_auth_jwt:check_auth/3),
+    emqx_modules:refresh_module(jwt_authentication);
+maybe_refresh_jwt_module(_) ->
+    ok.
+
+-else.
+
+maybe_refresh_jwt_module(_) ->
+    ok.
+
+-endif.
diff --git a/test/emqx_channel_SUITE.erl b/test/emqx_channel_SUITE.erl
index 6ccbcc16b..211edc2b1 100644
--- a/test/emqx_channel_SUITE.erl
+++ b/test/emqx_channel_SUITE.erl
@@ -205,7 +205,8 @@ t_handle_in_qos2_publish_with_error_return(_) ->
     ok = meck:expect(emqx_metrics, inc, fun(_) -> ok end),
     ok = meck:expect(emqx_broker, publish, fun(_) -> [] end),
     Session = session(#{max_awaiting_rel => 2, awaiting_rel => #{1 => 1}}),
-    Channel = channel(#{conn_state => connected, session => Session}),
+    Channel = emqx_channel:ensure_timer(await_timer, 2000,
+        channel(#{conn_state => connected, session => Session})),
     Publish1 = ?PUBLISH_PACKET(?QOS_2, <<"topic">>, 1, <<"payload">>),
     {ok, ?PUBREC_PACKET(1, ?RC_PACKET_IDENTIFIER_IN_USE), Channel} =
         emqx_channel:handle_in(Publish1, Channel),
diff --git a/test/emqx_client_SUITE.erl b/test/emqx_client_SUITE.erl
index d45e7a8cf..83fe09e13 100644
--- a/test/emqx_client_SUITE.erl
+++ b/test/emqx_client_SUITE.erl
@@ -41,12 +41,24 @@
                       <<"TopicA/#">>
                      ]).
 
+-define(do_receive_tcp_packet(TIMEOUT, SOCKET, PACKET, EXPRESS),
+    receive
+        {tcp, SOCKET, PACKET} -> EXPRESS
+    after TIMEOUT ->
+        ct:fail({receive_timeout, TIMEOUT})
+    end).
+
+-define(receive_tcp_packet(TIMEOUT, SOCKET, PACKET, EXPRESS),
+    fun() ->
+        ?do_receive_tcp_packet(TIMEOUT, SOCKET, PACKET, EXPRESS)
+    end()).
 
 all() ->
     [{group, mqttv3},
      {group, mqttv4},
      {group, mqttv5},
-     {group, others}
+     {group, others},
+     {group, bugfixes}
     ].
 
 groups() ->
@@ -73,6 +85,10 @@ groups() ->
        t_certcn_as_clientid_default_config_tls,
        t_certcn_as_clientid_tlsv1_3,
        t_certcn_as_clientid_tlsv1_2
+      ]},
+     {bugfixes, [non_parallel_tests],
+      [ t_qos2_no_pubrel_received
+      , t_retry_timer_after_session_taken_over
       ]}
     ].
 
@@ -84,6 +100,18 @@ init_per_suite(Config) ->
 end_per_suite(_Config) ->
     emqx_ct_helpers:stop_apps([]).
 
+init_per_testcase(Func, Cfg) ->
+    maybe_run_fun(setup, Func, Cfg).
+
+end_per_testcase(Func, Cfg) ->
+    maybe_run_fun(teardown, Func, Cfg).
+
+maybe_run_fun(Tag, Func, Cfg) ->
+    try ?MODULE:Func(Tag, Cfg)
+    catch
+        error:undef -> Cfg
+    end.
+
 set_special_confs(emqx) ->
     emqx_ct_helpers:change_emqx_opts(ssl_twoway, [{peer_cert_as_username, cn}]);
 set_special_confs(_) ->
@@ -297,12 +325,193 @@ t_certcn_as_clientid_tlsv1_3(_) ->
 t_certcn_as_clientid_tlsv1_2(_) ->
     tls_certcn_as_clientid('tlsv1.2').
 
+t_qos2_no_pubrel_received(setup, Cfg) ->
+    OldMaxAwaitRel = emqx_zone:get_env(external, max_awaiting_rel),
+    OldWaitTimeout = emqx_zone:get_env(external, await_rel_timeout),
+    emqx_zone:set_env(external, max_awaiting_rel, 2),
+    emqx_zone:set_env(external, await_rel_timeout, 1),
+    [{old_max_await_rel, OldMaxAwaitRel},
+     {old_wait_timeout, OldWaitTimeout} | Cfg];
+t_qos2_no_pubrel_received(teardown, Cfg) ->
+    OldMaxAwaitRel = ?config(old_max_await_rel, Cfg),
+    OldWaitTimeout = ?config(old_wait_timeout, Cfg),
+    emqx_zone:set_env(external, max_awaiting_rel, OldMaxAwaitRel),
+    emqx_zone:set_env(external, await_rel_timeout, OldWaitTimeout).
+t_qos2_no_pubrel_received(_) ->
+    %% [The Scenario]:
+    %% Client --- CONN: clean_session=false --> EMQX
+    %% Client --- PUB: QoS2 ---> EMQX
+    %% Client --- PUB: QoS2 ---> EMQX
+    %% Client --- ...       ---> EMQX
+    %% Client <---- PUBREC ---- EMQX
+    %% Client <---- PUBREC ---- EMQX
+    %% Client <---- ...    ---- EMQX
+    %% Client --- PUBREL --X--> EMQX (PUBREL not received)
+    %% Client <--- DISCONN: RC_RECEIVE_MAXIMUM_EXCEEDED --- EMQX
+    %%
+    %% [A few hours later..]:
+    %% Client --- CONN: clean_session=false --> EMQX
+    %% Client --- PUB: QoS2 ---> EMQX
+    %% Client <--- DISCONN: RC_RECEIVE_MAXIMUM_EXCEEDED --- EMQX (we should clear the awaiting_rel queue but it is still full).
+    ct:pal("1. reconnect after awaiting_rel is cleared"),
+    qos2_no_pubrel_received(fun
+        (1) -> timer:sleep(1500); %% reconnect 1.5s later, ensure the await_rel_timeout triggered
+        (2) -> ok
+    end),
+    ct:pal("2. reconnect before awaiting_rel is cleared"),
+    qos2_no_pubrel_received(fun
+        (1) -> ok; %% reconnect as fast as possiable, ensure the await_rel_timeout NOT triggered
+        (2) -> timer:sleep(1500) %% send msgs 1.5s later, ensure the await_rel_timeout triggered
+    end).
 
+qos2_no_pubrel_received(Actions) ->
+    ClientId = emqx_guid:to_hexstr(emqx_guid:gen()),
+    Topic = <<"t/foo">>,
+    {ok, Sock} = gen_tcp:connect("127.0.0.1", 1883, [], 3000),
+    gen_tcp:send(Sock, make_connect_packet(ClientId, false)),
+    timer:sleep(100),
+    ok = gen_tcp:send(Sock, make_publish_packet(Topic, 2, 100, <<"foo">>)),
+    ok = gen_tcp:send(Sock, make_publish_packet(Topic, 2, 101, <<"foo">>)),
+    %% Send the 3rd publish with id 103 will got disconnected:
+    %%  - "Dropped the qos2 packet 103 due to awaiting_rel is full".
+    ?assertMatch(ok, gen_tcp:send(Sock, make_publish_packet(Topic, 2, 103, <<"foo">>))),
+    %% not the connections should be closed by the server due to ?RC_RECEIVE_MAXIMUM_EXCEEDED
+    receive
+        {tcp_closed, Sock} -> ok
+    after 500 ->
+        ct:fail({wait_tcp_close_timeout, 500})
+    end,
+
+    %% before reconnecting
+    action_point(Actions, 1),
+
+    {ok, Sock1} = gen_tcp:connect("127.0.0.1", 1883, [], 3000),
+    gen_tcp:send(Sock1, make_connect_packet(ClientId, false)),
+
+    %% after connected and before sending any msgs
+    action_point(Actions, 2),
+
+    ok = gen_tcp:send(Sock1, make_publish_packet(Topic, 2, 104, <<"foo">>)),
+
+    receive
+        {tcp_closed, Sock1} ->
+            %% this is the bug, the wait_rel queue should have expired but not cleared
+            ct:fail(unexpected_disconnect)
+    after 500 -> ok
+    end,
+    gen_tcp:close(Sock1),
+    ok.
+
+t_retry_timer_after_session_taken_over(setup, Cfg) ->
+    %emqx_logger:set_log_level(debug),
+    OldRetryInterval = emqx_zone:get_env(external, retry_interval),
+    emqx_zone:set_env(external, retry_interval, 1),
+    [{old_retry_interval, OldRetryInterval} | Cfg];
+t_retry_timer_after_session_taken_over(teardown, Cfg) ->
+    %emqx_logger:set_log_level(warning),
+    OldRetryInterval = ?config(old_retry_interval, Cfg),
+    emqx_zone:set_env(external, retry_interval, OldRetryInterval).
+t_retry_timer_after_session_taken_over(_) ->
+    %% [The Scenario]:
+    %% Client --- CONN: clean_session=false --> EMQX
+    %% Client <--- PUB: QoS1 --- EMQX
+    %% Client --X-- PUBACK ----> EMQX (the client doesn't send PUBACK)
+    %% Client <---- PUB: QoS1 ---- EMQX (resend the PUBLISH msg)
+    %% Client --- DISCONN ---> EMQX
+    %% [A few seconds later..]:
+    %% Client --- CONN: clean_session=false --> EMQX
+    %% Client <--- PUB: QoS1 --- EMQX (resume session and resend the inflight messages)
+    %% Client --X-- PUBACK ----> EMQX (the client doesn't send PUBACK)
+    TcpOpts = [binary, {active, true}],
+
+    ClientId = emqx_guid:to_hexstr(emqx_guid:gen()),
+    Topic = <<"t/foo">>,
+    Payload = <<"DO NOT REPLY!">>,
+
+    %% CONNECT
+    {ok, Sock1} = gen_tcp:connect("127.0.0.1", 1883, TcpOpts, 3000),
+    ok = gen_tcp:send(Sock1, make_connect_packet(ClientId, false)),
+    ?receive_tcp_packet(1000, Sock1, _, ok),
+
+    %% SUBSCRIBE
+    ok = gen_tcp:send(Sock1, make_subscribe_packet(Topic, 2, 1)),
+    ?receive_tcp_packet(200, Sock1, _, ok),
+
+    emqx_broker:publish(emqx_message:make(<<"publisher">>, 1, Topic, Payload)),
+    %% note that here we don't reply the publish with puback
+    ?receive_tcp_packet(200, Sock1, PubPacket1,
+        begin
+            ?assertMatch({ok, ?PUBLISH_PACKET(1, Topic, 1, Payload), <<>>, _},
+                emqx_frame:parse(PubPacket1))
+        end),
+
+    ok = gen_tcp:close(Sock1),
+    timer:sleep(100),
+
+    %% CONNECT again
+    {ok, Sock2} = gen_tcp:connect("127.0.0.1", 1883, TcpOpts, 3000),
+    ok = gen_tcp:send(Sock2, make_connect_packet(ClientId, false)),
+    ConnAckRem = ?do_receive_tcp_packet(200, Sock2, ConnPack2, begin
+        ConnAck = iolist_to_binary(make_connack_packet(?CONNACK_ACCEPT, 1)),
+        ct:pal("--- connack: ~p, got: ~p", [ConnAck, ConnPack2]),
+        <<ConnAck:4/binary, Rem/binary>> = ConnPack2,
+        Rem
+    end),
+
+    %% emqx should resend the non-ACKed messages now
+    PubPacket2 = case ConnAckRem of
+        <<>> ->
+            ?receive_tcp_packet(200, Sock2, Packet, Packet);
+        _ ->
+            ConnAckRem
+    end,
+    ?assertMatch({ok, ?PUBLISH_PACKET(1, Topic, 1, Payload), <<>>, _},
+        emqx_frame:parse(PubPacket2)),
+
+    %% ... and emqx should resend the message 1s later, as we didn't ACK it.
+    ?receive_tcp_packet(1200, Sock2, Packet,
+        begin
+            ?assertMatch({ok, ?PUBLISH_PACKET(1, Topic, 1, Payload), <<>>, _},
+                emqx_frame:parse(Packet))
+        end),
+
+    %% we ACK it now, then emqx should stop the resending
+    ok = gen_tcp:send(Sock2, make_connect_packet(ClientId, false)),
+    receive
+        {tcp, Sock2, _PACKET} ->
+            {ok, MqttPacket, <<>>, _} = emqx_frame:parse(_PACKET),
+            ?assertNotMatch(?PUBLISH_PACKET(_), MqttPacket)
+    after 1200 -> ok
+    end,
+    ok = gen_tcp:close(Sock1).
 
 %%--------------------------------------------------------------------
 %% Helper functions
 %%--------------------------------------------------------------------
 
+action_point(Action, N) ->
+    Action(N).
+
+make_connect_packet(ClientId, CleanStart) ->
+    emqx_frame:serialize(?CONNECT_PACKET(
+        #mqtt_packet_connect{
+            proto_name = <<"MQTT">>,
+            clean_start = CleanStart,
+            keepalive = 0,
+            clientid = ClientId
+        }
+    )).
+make_connack_packet(Code, SP) ->
+    emqx_frame:serialize(?CONNACK_PACKET(Code, SP)).
+
+make_publish_packet(Topic, QoS, PacketId, Payload) ->
+    emqx_frame:serialize(
+        ?PUBLISH_PACKET(QoS, Topic, PacketId, Payload)).
+
+make_subscribe_packet(TopicFileter, QoS, PacketId) ->
+    emqx_frame:serialize(
+        ?SUBSCRIBE_PACKET(PacketId, [{TopicFileter, #{rh => 0, rap => 0, nl => 0, qos => QoS}}])).
+
 recv_msgs(Count) ->
     recv_msgs(Count, []).