diff --git a/include/libs/stream/tstream.h b/include/libs/stream/tstream.h
index 2ce640a2bc..329a6bbc29 100644
--- a/include/libs/stream/tstream.h
+++ b/include/libs/stream/tstream.h
@@ -45,7 +45,7 @@ enum {
   TASK_STATUS__FAIL,
   TASK_STATUS__STOP,
   TASK_STATUS__SCAN_HISTORY,  // stream task scan history data by using tsdbread in the stream scanner
-  TASK_STATUS__HALT,          // stream task will handle all data in the input queue, and then paused
+  TASK_STATUS__HALT,          // stream task will handle all data in the input queue, and then paused, todo remove it?
   TASK_STATUS__PAUSE,         // pause
 };
 
@@ -272,6 +272,7 @@ typedef struct SStreamStatus {
   int8_t        keepTaskStatus;
   bool          transferState;
   int8_t        timerActive;     // timer is active
+  int8_t        pauseAllowed;    // allowed task status to be set to be paused
 } SStreamStatus;
 
 typedef struct SHistDataRange {
@@ -557,7 +558,6 @@ int32_t streamProcessDispatchMsg(SStreamTask* pTask, SStreamDispatchReq* pReq, S
 int32_t streamProcessDispatchRsp(SStreamTask* pTask, SStreamDispatchRsp* pRsp, int32_t code);
 
 int32_t streamProcessRetrieveReq(SStreamTask* pTask, SStreamRetrieveReq* pReq, SRpcMsg* pMsg);
-// int32_t streamProcessRetrieveRsp(SStreamTask* pTask, SStreamRetrieveRsp* pRsp);
 
 void    streamTaskInputFail(SStreamTask* pTask);
 int32_t streamTryExec(SStreamTask* pTask);
@@ -593,6 +593,9 @@ int32_t     streamSetParamForScanHistory(SStreamTask* pTask);
 int32_t     streamRestoreParam(SStreamTask* pTask);
 int32_t     streamSetStatusNormal(SStreamTask* pTask);
 const char* streamGetTaskStatusStr(int32_t status);
+void        streamTaskPause(SStreamTask* pTask);
+void        streamTaskDisablePause(SStreamTask* pTask);
+void        streamTaskEnablePause(SStreamTask* pTask);
 
 // source level
 int32_t streamSetParamForStreamScannerStep1(SStreamTask* pTask, SVersionRange* pVerRange, STimeWindow* pWindow);
diff --git a/source/dnode/mnode/impl/src/mndScheduler.c b/source/dnode/mnode/impl/src/mndScheduler.c
index 7cb52d2bc9..8984b798ab 100644
--- a/source/dnode/mnode/impl/src/mndScheduler.c
+++ b/source/dnode/mnode/impl/src/mndScheduler.c
@@ -25,6 +25,7 @@
 #define SINK_NODE_LEVEL (0)
 extern bool tsDeployOnSnode;
 
+static int32_t setTaskUpstreamEpInfo(const SStreamTask* pTask, SStreamTask* pDownstream);
 static int32_t mndAddSinkTaskToStream(SStreamObj* pStream, SArray* pTaskList, SMnode* pMnode, int32_t vgId,
                                       SVgObj* pVgroup, int32_t fillHistory);
 static void    setFixedDownstreamEpInfo(SStreamTask* pDstTask, const SStreamTask* pTask);
@@ -267,10 +268,15 @@ static int32_t addSourceStreamTask(SMnode* pMnode, SVgObj* pVgroup, SArray* pTas
     return terrno;
   }
 
+  for(int32_t i = 0; i < taosArrayGetSize(pSinkTaskList); ++i) {
+    SStreamTask* pSinkTask = taosArrayGetP(pSinkTaskList, i);
+    setTaskUpstreamEpInfo(pTask, pSinkTask);
+  }
+
   return TSDB_CODE_SUCCESS;
 }
 
-static SStreamChildEpInfo* createStreamTaskEpInfo(SStreamTask* pTask) {
+static SStreamChildEpInfo* createStreamTaskEpInfo(const SStreamTask* pTask) {
   SStreamChildEpInfo* pEpInfo = taosMemoryMalloc(sizeof(SStreamChildEpInfo));
   if (pEpInfo == NULL) {
     terrno = TSDB_CODE_OUT_OF_MEMORY;
@@ -295,7 +301,7 @@ void setFixedDownstreamEpInfo(SStreamTask* pDstTask, const SStreamTask* pTask) {
   pDstTask->msgInfo.msgType = TDMT_STREAM_TASK_DISPATCH;
 }
 
-int32_t setEpToDownstreamTask(SStreamTask* pTask, SStreamTask* pDownstream) {
+int32_t setTaskUpstreamEpInfo(const SStreamTask* pTask, SStreamTask* pDownstream) {
   SStreamChildEpInfo* pEpInfo = createStreamTaskEpInfo(pTask);
   if (pEpInfo == NULL) {
     return TSDB_CODE_OUT_OF_MEMORY;
@@ -418,7 +424,7 @@ static int32_t doAddSourceTask(SArray* pTaskList, int8_t fillHistory, int64_t ui
     return -1;
   }
 
-  return setEpToDownstreamTask(pTask, pDownstreamTask);
+  return setTaskUpstreamEpInfo(pTask, pDownstreamTask);
 }
 
 static int32_t doAddAggTask(uint64_t uid, SArray* pTaskList, SArray* pSinkNodeList, SMnode* pMnode, SStreamObj* pStream,
@@ -586,6 +592,14 @@ static int32_t addSinkTasks(SArray* pTasksList, SMnode* pMnode, SStreamObj* pStr
   return TSDB_CODE_SUCCESS;
 }
 
+static void setSinkTaskUpstreamInfo(SArray* pTasksList, const SStreamTask* pUpstreamTask) {
+  SArray* pSinkTaskList = taosArrayGetP(pTasksList, SINK_NODE_LEVEL);
+  for(int32_t i = 0; i < taosArrayGetSize(pSinkTaskList); ++i) {
+    SStreamTask* pSinkTask = taosArrayGetP(pSinkTaskList, i);
+    setTaskUpstreamEpInfo(pUpstreamTask, pSinkTask);
+  }
+}
+
 static int32_t doScheduleStream(SStreamObj* pStream, SMnode* pMnode, SQueryPlan* pPlan, int64_t nextWindowSkey) {
   SSdb*   pSdb = pMnode->pSdb;
   int32_t numOfPlanLevel = LIST_LENGTH(pPlan->pSubplans);
@@ -637,6 +651,9 @@ static int32_t doScheduleStream(SStreamObj* pStream, SMnode* pMnode, SQueryPlan*
       return code;
     }
 
+    setSinkTaskUpstreamInfo(pStream->tasks, pAggTask);
+    setSinkTaskUpstreamInfo(pStream->pHTasksList, pHAggTask);
+
     // source level
     return addSourceTasksForMultiLevelStream(pMnode, pPlan, pStream, pAggTask, pHAggTask, nextWindowSkey);
   } else if (numOfPlanLevel == 1) {
diff --git a/source/dnode/vnode/src/tq/tq.c b/source/dnode/vnode/src/tq/tq.c
index 81176f8929..201c621ab3 100644
--- a/source/dnode/vnode/src/tq/tq.c
+++ b/source/dnode/vnode/src/tq/tq.c
@@ -914,6 +914,12 @@ int32_t tqExpandTask(STQ* pTq, SStreamTask* pTask, int64_t ver) {
     pTask->exec.pWalReader = walOpenReader(pTq->pVnode->pWal, &cond);
   }
 
+  // reset the task status from unfinished transaction
+  if (pTask->status.taskStatus == TASK_STATUS__PAUSE) {
+    tqWarn("s-task:%s reset task status to be normal, kept in meta status: Paused", pTask->id.idStr);
+    pTask->status.taskStatus = TASK_STATUS__NORMAL;
+  }
+
   streamSetupScheduleTrigger(pTask);
 
   tqInfo("vgId:%d expand stream task, s-task:%s, checkpoint ver:%" PRId64
@@ -1031,9 +1037,11 @@ int32_t tqProcessTaskDeployReq(STQ* pTq, int64_t sversion, char* msg, int32_t ms
   SStreamMeta* pStreamMeta = pTq->pStreamMeta;
 
   // 2.save task, use the newest commit version as the initial start version of stream task.
+  int32_t taskId = 0;
   taosWLockLatch(&pStreamMeta->lock);
   code = streamMetaAddDeployedTask(pStreamMeta, sversion, pTask);
 
+  taskId = pTask->id.taskId;
   int32_t numOfTasks = streamMetaGetNumOfTasks(pStreamMeta);
   if (code < 0) {
     tqError("vgId:%d failed to add s-task:%s, total:%d", vgId, pTask->id.idStr, numOfTasks);
@@ -1046,7 +1054,12 @@ int32_t tqProcessTaskDeployReq(STQ* pTq, int64_t sversion, char* msg, int32_t ms
           streamGetTaskStatusStr(pTask->status.taskStatus), numOfTasks);
 
   // 3. It's an fill history task, do nothing. wait for the main task to start it
-  streamTaskCheckDownstreamTasks(pTask);
+  SStreamTask* p = streamMetaAcquireTask(pStreamMeta, taskId);
+  if (p != NULL) {
+    streamTaskCheckDownstreamTasks(pTask);
+  }
+
+  streamMetaReleaseTask(pStreamMeta, p);
   return 0;
 }
 
@@ -1073,7 +1086,10 @@ int32_t tqProcessTaskScanHistory(STQ* pTq, SRpcMsg* pMsg) {
   int8_t  schedStatus = atomic_val_compare_exchange_8(&pTask->status.schedStatus, TASK_SCHED_STATUS__INACTIVE,
                                                       TASK_SCHED_STATUS__WAITING);
   if (schedStatus != TASK_SCHED_STATUS__INACTIVE) {
-    ASSERT(0);
+    tqDebug("s-task:%s failed to launch scan history data in current time window, unexpected sched status:%d", id,
+            schedStatus);
+
+    streamMetaReleaseTask(pMeta, pTask);
     return 0;
   }
 
@@ -1215,9 +1231,11 @@ int32_t tqProcessTaskTransferStateReq(STQ* pTq, SRpcMsg* pMsg) {
   int32_t code = tDecodeStreamScanHistoryFinishReq(&decoder, &req);
   tDecoderClear(&decoder);
 
+  tqDebug("vgId:%d start to process transfer state msg, from s-task:0x%x", pTq->pStreamMeta->vgId, req.taskId);
+
   SStreamTask* pTask = streamMetaAcquireTask(pTq->pStreamMeta, req.taskId);
   if (pTask == NULL) {
-    tqError("failed to find task:0x%x, it may have been dropped already", req.taskId);
+    tqError("failed to find task:0x%x, it may have been dropped already. process transfer state failed", req.taskId);
     return -1;
   }
 
@@ -1406,17 +1424,6 @@ int32_t tqProcessTaskDropReq(STQ* pTq, int64_t sversion, char* msg, int32_t msgL
   return 0;
 }
 
-// todo rule out the status when pause not suitable.
-static int32_t tqProcessTaskPauseImpl(SStreamMeta* pStreamMeta, SStreamTask* pTask) {
-  if (!streamTaskShouldPause(&pTask->status)) {
-    tqDebug("vgId:%d s-task:%s set pause flag", pStreamMeta->vgId, pTask->id.idStr);
-    atomic_store_8(&pTask->status.keepTaskStatus, pTask->status.taskStatus);
-    atomic_store_8(&pTask->status.taskStatus, TASK_STATUS__PAUSE);
-  }
-
-  return 0;
-}
-
 int32_t tqProcessTaskPauseReq(STQ* pTq, int64_t sversion, char* msg, int32_t msgLen) {
   SVPauseStreamTaskReq* pReq = (SVPauseStreamTaskReq*)msg;
 
@@ -1425,30 +1432,29 @@ int32_t tqProcessTaskPauseReq(STQ* pTq, int64_t sversion, char* msg, int32_t msg
   if (pTask == NULL) {
     tqError("vgId:%d failed to acquire task:0x%x, it may have been dropped already", pMeta->vgId,
             pReq->taskId);
-    return TSDB_CODE_STREAM_TASK_NOT_EXIST;
+
+    // since task is in [STOP|DROPPING] state, it is safe to assume the pause is active
+    return TSDB_CODE_SUCCESS;
   }
 
   tqDebug("s-task:%s receive pause msg from mnode", pTask->id.idStr);
-
-  int32_t code = tqProcessTaskPauseImpl(pMeta, pTask);
-  if (code != 0) {
-    streamMetaReleaseTask(pMeta, pTask);
-    return code;
-  }
+  streamTaskPause(pTask);
 
   SStreamTask* pHistoryTask = NULL;
   if (pTask->historyTaskId.taskId != 0) {
     pHistoryTask = streamMetaAcquireTask(pMeta, pTask->historyTaskId.taskId);
     if (pHistoryTask == NULL) {
-      tqError("vgId:%d failed to acquire fill-history task:0x%x, it may have been dropped already", pMeta->vgId,
-              pTask->historyTaskId.taskId);
+      tqError("vgId:%d failed to acquire fill-history task:0x%x, it may have been dropped already. Pause success",
+              pMeta->vgId, pTask->historyTaskId.taskId);
 
       streamMetaReleaseTask(pMeta, pTask);
-      return TSDB_CODE_STREAM_TASK_NOT_EXIST;
+
+      // since task is in [STOP|DROPPING] state, it is safe to assume the pause is active
+      return TSDB_CODE_SUCCESS;
     }
 
-    tqDebug("s-task:%s fill-history task handle pause along with related stream task", pHistoryTask->id.idStr);
-    code = tqProcessTaskPauseImpl(pMeta, pHistoryTask);
+    tqDebug("s-task:%s fill-history task handle paused along with related stream task", pHistoryTask->id.idStr);
+    streamTaskPause(pHistoryTask);
   }
 
   streamMetaReleaseTask(pMeta, pTask);
@@ -1456,7 +1462,7 @@ int32_t tqProcessTaskPauseReq(STQ* pTq, int64_t sversion, char* msg, int32_t msg
     streamMetaReleaseTask(pMeta, pHistoryTask);
   }
 
-  return code;
+  return TSDB_CODE_SUCCESS;
 }
 
 int32_t tqProcessTaskResumeImpl(STQ* pTq, SStreamTask* pTask, int64_t sversion, int8_t igUntreated) {
diff --git a/source/libs/stream/src/streamExec.c b/source/libs/stream/src/streamExec.c
index 0a248d0ffe..0654bcf69f 100644
--- a/source/libs/stream/src/streamExec.c
+++ b/source/libs/stream/src/streamExec.c
@@ -365,6 +365,10 @@ static int32_t streamTransferStateToStreamTask(SStreamTask* pTask) {
            pStreamTask->id.idStr);
   }
 
+  // todo fix race condition
+  streamTaskDisablePause(pTask);
+  streamTaskDisablePause(pStreamTask);
+
   ASSERT(pStreamTask->historyTaskId.taskId == pTask->id.taskId && pTask->status.transferState == true);
 
   STimeWindow* pTimeWindow = &pStreamTask->dataRange.window;
@@ -420,6 +424,10 @@ static int32_t streamTransferStateToStreamTask(SStreamTask* pTask) {
   }
   taosWUnLockLatch(&pMeta->lock);
 
+  // pause allowed
+  streamTaskEnablePause(pStreamTask);
+  streamTaskEnablePause(pTask);
+
   streamSchedExec(pStreamTask);
   streamMetaReleaseTask(pMeta, pStreamTask);
   return TSDB_CODE_SUCCESS;
@@ -568,22 +576,7 @@ int32_t streamExecForAll(SStreamTask* pTask) {
 }
 
 bool streamTaskIsIdle(const SStreamTask* pTask) {
-  int32_t numOfItems = taosQueueItemSize(pTask->inputQueue->queue);
-  if (numOfItems > 0) {
-    return false;
-  }
-
-  numOfItems = taosQallItemSize(pTask->inputQueue->qall);
-  if (numOfItems > 0) {
-    return false;
-  }
-
-  // blocked by downstream task
-  if (pTask->outputInfo.status == TASK_OUTPUT_STATUS__BLOCKED) {
-    return false;
-  }
-
-  return (pTask->status.schedStatus == TASK_SCHED_STATUS__INACTIVE);
+  return (pTask->status.schedStatus == TASK_SCHED_STATUS__INACTIVE/* && pTask->status.taskStatus != TASK_STATUS__HALT*/);
 }
 
 int32_t streamTryExec(SStreamTask* pTask) {
diff --git a/source/libs/stream/src/streamRecover.c b/source/libs/stream/src/streamRecover.c
index ddd7ae4676..d3687c3845 100644
--- a/source/libs/stream/src/streamRecover.c
+++ b/source/libs/stream/src/streamRecover.c
@@ -72,7 +72,9 @@ static int32_t doLaunchScanHistoryTask(SStreamTask* pTask) {
 int32_t streamTaskLaunchScanHistory(SStreamTask* pTask) {
   if (pTask->info.taskLevel == TASK_LEVEL__SOURCE) {
     if (pTask->status.taskStatus == TASK_STATUS__SCAN_HISTORY) {
-      return doLaunchScanHistoryTask(pTask);
+      int32_t code = doLaunchScanHistoryTask(pTask);
+      streamTaskEnablePause(pTask);
+      return code;
     } else {
       ASSERT(pTask->status.taskStatus == TASK_STATUS__NORMAL);
       qDebug("s-task:%s no need to scan-history-data, status:%s, sched-status:%d, ver:%" PRId64, pTask->id.idStr,
@@ -86,6 +88,7 @@ int32_t streamTaskLaunchScanHistory(SStreamTask* pTask) {
     qDebug("s-task:%s sink task do nothing to handle scan-history", pTask->id.idStr);
   }
 
+  streamTaskEnablePause(pTask);
   return 0;
 }
 
@@ -198,6 +201,11 @@ static void doProcessDownstreamReadyRsp(SStreamTask* pTask, int32_t numOfReqs) {
     qDebug("s-task:%s downstream tasks are ready, now ready for data from wal, status:%s", id, str);
   }
 
+  // enable pause when init completed.
+  if (pTask->historyTaskId.taskId == 0 && pTask->info.fillHistory == 0) {
+    streamTaskEnablePause(pTask);
+  }
+
   // when current stream task is ready, check the related fill history task.
   launchFillHistoryTask(pTask);
 }
@@ -415,8 +423,8 @@ int32_t streamDispatchTransferStateMsg(SStreamTask* pTask) {
 // agg
 int32_t streamAggScanHistoryPrepare(SStreamTask* pTask) {
   pTask->numOfWaitingUpstream = taosArrayGetSize(pTask->pUpstreamEpInfoList);
-  qDebug("s-task:%s agg task is ready and wait for %d upstream tasks complete scan-history procedure", pTask->id.idStr,
-         pTask->numOfWaitingUpstream);
+  qDebug("s-task:%s agg task wait for %d upstream tasks complete scan-history procedure, status:%s", pTask->id.idStr,
+         pTask->numOfWaitingUpstream, streamGetTaskStatusStr(pTask->status.taskStatus));
   return 0;
 }
 
@@ -745,7 +753,6 @@ void launchFillHistoryTask(SStreamTask* pTask) {
   streamLaunchFillHistoryTask(pTask);
 }
 
-// todo handle race condition, this task may be destroyed
 void streamTaskCheckDownstreamTasks(SStreamTask* pTask) {
   if (pTask->info.fillHistory) {
     qDebug("s-task:%s fill history task, wait for being launched", pTask->id.idStr);
@@ -757,3 +764,37 @@ void streamTaskCheckDownstreamTasks(SStreamTask* pTask) {
   // check downstream tasks for itself
   streamTaskDoCheckDownstreamTasks(pTask);
 }
+
+void streamTaskPause(SStreamTask* pTask) {
+  SStreamMeta* pMeta = pTask->pMeta;
+
+  int64_t st = taosGetTimestampMs();
+  while(!pTask->status.pauseAllowed) {
+    qDebug("s-task:%s wait for the task can be paused, vgId:%d", pTask->id.idStr, pMeta->vgId);
+    taosMsleep(100);
+  }
+
+  atomic_store_8(&pTask->status.keepTaskStatus, pTask->status.taskStatus);
+  atomic_store_8(&pTask->status.taskStatus, TASK_STATUS__PAUSE);
+
+  int64_t el = taosGetTimestampMs() - st;
+  qDebug("vgId:%d s-task:%s set pause flag, prev:%s, elapsed time:%dms", pMeta->vgId, pTask->id.idStr,
+         streamGetTaskStatusStr(pTask->status.keepTaskStatus), el);
+}
+
+// todo fix race condition
+void streamTaskDisablePause(SStreamTask* pTask) {
+  // pre-condition check
+  while (pTask->status.taskStatus == TASK_STATUS__PAUSE) {
+    taosMsleep(10);
+    qDebug("s-task:%s already in pause, wait for pause being cancelled, and then set pause disabled", pTask->id.idStr);
+  }
+
+  qDebug("s-task:%s disable task pause", pTask->id.idStr);
+  pTask->status.pauseAllowed = 0;
+}
+
+void streamTaskEnablePause(SStreamTask* pTask) {
+  qDebug("s-task:%s enable task pause", pTask->id.idStr);
+  pTask->status.pauseAllowed = 1;
+}
\ No newline at end of file