diff --git a/src/cq/src/cqMain.c b/src/cq/src/cqMain.c
index 7935bb7ff5..5cc3ce0159 100644
--- a/src/cq/src/cqMain.c
+++ b/src/cq/src/cqMain.c
@@ -18,6 +18,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <pthread.h>
+#include <errno.h>
 #include "taosdef.h"
 #include "taosmsg.h"
 #include "tglobal.h"
@@ -64,7 +65,10 @@ static void cqCreateStream(SCqContext *pContext, SCqObj *pObj);
 void *cqOpen(void *ahandle, const SCqCfg *pCfg) {
   
   SCqContext *pContext = calloc(sizeof(SCqContext), 1);
-  if (pContext == NULL) return NULL;
+  if (pContext == NULL) {
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return NULL;
+  }
 
   strcpy(pContext->user, pCfg->user);
   strcpy(pContext->pass, pCfg->pass);
@@ -82,6 +86,7 @@ void *cqOpen(void *ahandle, const SCqCfg *pCfg) {
 
 void cqClose(void *handle) {
   SCqContext *pContext = handle;
+  if (handle == NULL) return;
 
   // stop all CQs
   cqStop(pContext);
@@ -106,9 +111,9 @@ void cqClose(void *handle) {
 
 void cqStart(void *handle) {
   SCqContext *pContext = handle;
-  cTrace("vgId:%d, start all CQs", pContext->vgId);
   if (pContext->dbConn || pContext->master) return;
 
+  cTrace("vgId:%d, start all CQs", pContext->vgId);
   pthread_mutex_lock(&pContext->mutex);
 
   pContext->master = 1;
diff --git a/src/inc/tsync.h b/src/inc/tsync.h
index 05d1d93cf6..fcf26d22c3 100644
--- a/src/inc/tsync.h
+++ b/src/inc/tsync.h
@@ -94,8 +94,8 @@ typedef void* tsync_h;
 
 tsync_h syncStart(const SSyncInfo *);
 void    syncStop(tsync_h shandle);
-int     syncReconfig(tsync_h shandle, const SSyncCfg *);
-int     syncForwardToPeer(tsync_h shandle, void *pHead, void *mhandle, int qtype);
+int32_t syncReconfig(tsync_h shandle, const SSyncCfg *);
+int32_t syncForwardToPeer(tsync_h shandle, void *pHead, void *mhandle, int qtype);
 void    syncConfirmForward(tsync_h shandle, uint64_t version, int32_t code);
 void    syncRecover(tsync_h shandle);      // recover from other nodes:
 int     syncGetNodesRole(tsync_h shandle, SNodesRole *);
diff --git a/src/util/src/tqueue.c b/src/util/src/tqueue.c
index 1e248c9e45..475941dbdb 100644
--- a/src/util/src/tqueue.c
+++ b/src/util/src/tqueue.c
@@ -65,6 +65,7 @@ taos_queue taosOpenQueue() {
 }
 
 void taosCloseQueue(taos_queue param) {
+  if (param == NULL) return;
   STaosQueue *queue = (STaosQueue *)param;
   STaosQnode *pTemp;
   STaosQnode *pNode = queue->head;  
@@ -224,6 +225,7 @@ taos_qset taosOpenQset() {
 }
 
 void taosCloseQset(taos_qset param) {
+  if (param == NULL) return;
   STaosQset *qset = (STaosQset *)param;
   pthread_mutex_destroy(&qset->mutex);
   tsem_destroy(&qset->sem);
diff --git a/src/util/src/ttimer.c b/src/util/src/ttimer.c
index 42fd13b2cd..e6ef73ef57 100644
--- a/src/util/src/ttimer.c
+++ b/src/util/src/ttimer.c
@@ -405,19 +405,19 @@ static bool doStopTimer(tmr_obj_t* timer, uint8_t state) {
     tmrTrace(fmt, timer->ctrl->label, timer->id, timer->fp, timer->param);
     return reusable;
   }
-  
+
   if (state != TIMER_STATE_EXPIRED) {
     // timer already stopped or cancelled, has nothing to do in this case
     return false;
   }
-  
+
   if (timer->executedBy == taosGetPthreadId()) {
     // taosTmrReset is called in the timer callback, should do nothing in this
     // case to avoid dead lock. note taosTmrReset must be the last statement
     // of the callback funtion, will be a bug otherwise.
     return false;
   }
-  
+
   // timer callback is executing in another thread, we SHOULD wait it to stop,
   // BUT this may result in dead lock if current thread are holding a lock which
   // the timer callback need to acquire. so, we HAVE TO return directly.
@@ -501,6 +501,7 @@ static void taosTmrModuleInit(void) {
     tmr_ctrl_t* ctrl = tmrCtrls + i;
     ctrl->next = ctrl + 1;
   }
+  (tmrCtrls + taosMaxTmrCtrl - 1)->next = NULL;
   unusedTmrCtrl = tmrCtrls;
 
   pthread_mutex_init(&tmrCtrlMutex, NULL);
@@ -574,12 +575,12 @@ void taosTmrCleanUp(void* handle) {
 
   if (numOfTmrCtrl <=0) {
     taosUninitTimer();
-    
+
     taosCleanUpScheduler(tmrQhandle);
 
     for (int i = 0; i < tListLen(wheels); i++) {
       time_wheel_t* wheel = wheels + i;
-      pthread_mutex_destroy(&wheel->mutex); 
+      pthread_mutex_destroy(&wheel->mutex);
       free(wheel->slots);
     }
 
diff --git a/src/vnode/src/vnodeMain.c b/src/vnode/src/vnodeMain.c
index 6f0b19b0c6..b8bc29550e 100644
--- a/src/vnode/src/vnodeMain.c
+++ b/src/vnode/src/vnodeMain.c
@@ -35,7 +35,7 @@ static void     vnodeCleanUp(SVnodeObj *pVnode);
 static int32_t  vnodeSaveCfg(SMDCreateVnodeMsg *pVnodeCfg);
 static int32_t  vnodeReadCfg(SVnodeObj *pVnode);
 static int32_t  vnodeSaveVersion(SVnodeObj *pVnode);
-static bool     vnodeReadVersion(SVnodeObj *pVnode);
+static int32_t  vnodeReadVersion(SVnodeObj *pVnode);
 static int      vnodeProcessTsdbStatus(void *arg, int status);
 static uint32_t vnodeGetFileInfo(void *ahandle, char *name, uint32_t *index, int32_t *size, uint64_t *fversion);
 static int      vnodeGetWalInfo(void *ahandle, char *name, uint32_t *index);
@@ -46,9 +46,9 @@ static pthread_once_t  vnodeModuleInit = PTHREAD_ONCE_INIT;
 
 #ifndef _SYNC
 tsync_h syncStart(const SSyncInfo *info) { return NULL; }
-int     syncForwardToPeer(tsync_h shandle, void *pHead, void *mhandle, int qtype) { return 0; }
+int32_t syncForwardToPeer(tsync_h shandle, void *pHead, void *mhandle, int qtype) { return 0; }
 void    syncStop(tsync_h shandle) {}
-int     syncReconfig(tsync_h shandle, const SSyncCfg * cfg) { return 0; }
+int32_t syncReconfig(tsync_h shandle, const SSyncCfg * cfg) { return 0; }
 int     syncGetNodesRole(tsync_h shandle, SNodesRole * cfg) { return 0; }
 void    syncConfirmForward(tsync_h shandle, uint64_t version, int32_t code) {}
 #endif
@@ -148,35 +148,20 @@ int32_t vnodeAlter(void *param, SMDCreateVnodeMsg *pVnodeCfg) {
   pVnode->status = TAOS_VN_STATUS_UPDATING;
 
   int32_t code = vnodeSaveCfg(pVnodeCfg);
-  if (code != TSDB_CODE_SUCCESS) {
-    vError("vgId:%d, failed to save vnode cfg, reason:%s", pVnodeCfg->cfg.vgId, tstrerror(code));
-    return code;
-  }
+  if (code != TSDB_CODE_SUCCESS) return code; 
 
   code = vnodeReadCfg(pVnode);
-  if (code != TSDB_CODE_SUCCESS) {
-    vError("vgId:%d, failed to read cfg file", pVnode->vgId);
-    taosHashRemove(tsDnodeVnodesHash, (const char *)&pVnode->vgId, sizeof(int32_t));
-    return code;
-  }
+  if (code != TSDB_CODE_SUCCESS) return code; 
 
   code = syncReconfig(pVnode->sync, &pVnode->syncCfg);
-  if (code != TSDB_CODE_SUCCESS) {
-    vTrace("vgId:%d, failed to alter vnode, canot reconfig sync, result:%s", pVnode->vgId,
-           tstrerror(code));
-    return code;
-  }
+  if (code != TSDB_CODE_SUCCESS) return code; 
 
   code = tsdbConfigRepo(pVnode->tsdb, &pVnode->tsdbCfg);
-  if (code != TSDB_CODE_SUCCESS) {
-    vTrace("vgId:%d, failed to alter vnode, canot reconfig tsdb, result:%s", pVnode->vgId,
-           tstrerror(code));
-    return code;
-  }
+  if (code != TSDB_CODE_SUCCESS) return code; 
 
   pVnode->status = TAOS_VN_STATUS_READY;
-
   vTrace("vgId:%d, vnode is altered", pVnode->vgId);
+
   return TSDB_CODE_SUCCESS;
 }
 
@@ -185,26 +170,40 @@ int32_t vnodeOpen(int32_t vnode, char *rootDir) {
   pthread_once(&vnodeModuleInit, vnodeInit);
 
   SVnodeObj *pVnode = calloc(sizeof(SVnodeObj), 1);
+  if (pVnode == NULL) {
+    vError("vgId:%d, failed to open vnode since no enough memory", vnode);
+    return TAOS_SYSTEM_ERROR(errno);
+  }
+
+  atomic_add_fetch_32(&tsOpennedVnodes, 1);
+  atomic_add_fetch_32(&pVnode->refCount, 1);
+
   pVnode->vgId     = vnode;
   pVnode->status   = TAOS_VN_STATUS_INIT;
-  pVnode->refCount = 1;
   pVnode->version  = 0;  
   pVnode->tsdbCfg.tsdbId = pVnode->vgId;
   pVnode->rootDir = strdup(rootDir);
-  taosHashPut(tsDnodeVnodesHash, (const char *)&pVnode->vgId, sizeof(int32_t), (char *)(&pVnode), sizeof(SVnodeObj *));
 
   int32_t code = vnodeReadCfg(pVnode);
   if (code != TSDB_CODE_SUCCESS) {
-    vError("vgId:%d, failed to read cfg file", pVnode->vgId);
-    taosHashRemove(tsDnodeVnodesHash, (const char *)&pVnode->vgId, sizeof(int32_t));
+    vnodeCleanUp(pVnode);
+    return code;
+  } 
+
+  code = vnodeReadVersion(pVnode);
+  if (code != TSDB_CODE_SUCCESS) {
+    vnodeCleanUp(pVnode);
     return code;
   }
 
-  vnodeReadVersion(pVnode);
   pVnode->fversion = pVnode->version;
   
   pVnode->wqueue = dnodeAllocateWqueue(pVnode);
   pVnode->rqueue = dnodeAllocateRqueue(pVnode);
+  if (pVnode->wqueue == NULL || pVnode->rqueue == NULL) {
+    vnodeCleanUp(pVnode);
+    return terrno;
+  }
 
   SCqCfg cqCfg = {0};
   sprintf(cqCfg.user, "root");
@@ -212,22 +211,29 @@ int32_t vnodeOpen(int32_t vnode, char *rootDir) {
   cqCfg.vgId = vnode;
   cqCfg.cqWrite = vnodeWriteToQueue;
   pVnode->cq = cqOpen(pVnode, &cqCfg);
+  if (pVnode->cq == NULL) {
+    vnodeCleanUp(pVnode);
+    return terrno;
+  }
 
   STsdbAppH appH = {0};
   appH.appH = (void *)pVnode;
   appH.notifyStatus = vnodeProcessTsdbStatus;
   appH.cqH = pVnode->cq;
-
   sprintf(temp, "%s/tsdb", rootDir);
   pVnode->tsdb = tsdbOpenRepo(temp, &appH);
   if (pVnode->tsdb == NULL) {
-    vError("vgId:%d, failed to open tsdb at %s(%s)", pVnode->vgId, temp, tstrerror(terrno));
-    taosHashRemove(tsDnodeVnodesHash, (const char *)&pVnode->vgId, sizeof(int32_t));
+    vnodeCleanUp(pVnode);
     return terrno;
   }
 
   sprintf(temp, "%s/wal", rootDir);
   pVnode->wal = walOpen(temp, &pVnode->walCfg);
+  if (pVnode->wal == NULL) { 
+    vnodeCleanUp(pVnode);
+    return terrno;
+  }
+
   walRestore(pVnode->wal, pVnode, vnodeWriteToQueue);
 
   SSyncInfo syncInfo;
@@ -246,6 +252,11 @@ int32_t vnodeOpen(int32_t vnode, char *rootDir) {
 
 #ifndef _SYNC
   pVnode->role = TAOS_SYNC_ROLE_MASTER;
+#else
+  if (pVnode->sync == NULL) {
+    vnodeCleanUp(pVnode);
+    return terrno;
+  }
 #endif
 
   // start continuous query
@@ -253,11 +264,11 @@ int32_t vnodeOpen(int32_t vnode, char *rootDir) {
     cqStart(pVnode->cq);
 
   pVnode->events = NULL;
-
   pVnode->status = TAOS_VN_STATUS_READY;
   vTrace("vgId:%d, vnode is opened in %s, pVnode:%p", pVnode->vgId, rootDir, pVnode);
 
-  atomic_add_fetch_32(&tsOpennedVnodes, 1);
+  taosHashPut(tsDnodeVnodesHash, (const char *)&pVnode->vgId, sizeof(int32_t), (char *)(&pVnode), sizeof(SVnodeObj *));
+
   return TSDB_CODE_SUCCESS;
 }
 
@@ -286,13 +297,6 @@ void vnodeRelease(void *pVnodeRaw) {
   }
 
   tfree(pVnode->rootDir);
-  // remove read queue
-  dnodeFreeRqueue(pVnode->rqueue);
-  pVnode->rqueue = NULL;
-
-  // remove write queue
-  dnodeFreeWqueue(pVnode->wqueue);
-  pVnode->wqueue = NULL;
 
   if (pVnode->status == TAOS_VN_STATUS_DELETING) {
     char rootDir[TSDB_FILENAME_LEN] = {0};
@@ -387,15 +391,26 @@ static void vnodeCleanUp(SVnodeObj *pVnode) {
     pVnode->sync = NULL;
   }
 
-  cqClose(pVnode->cq);
-  pVnode->cq = NULL;
-
-  tsdbCloseRepo(pVnode->tsdb, 1);
-  pVnode->tsdb = NULL;
-
-  walClose(pVnode->wal);
+  if (pVnode->wal) 
+    walClose(pVnode->wal);
   pVnode->wal = NULL;
 
+  if (pVnode->tsdb)
+    tsdbCloseRepo(pVnode->tsdb, 1);
+  pVnode->tsdb = NULL;
+
+  if (pVnode->cq) 
+    cqClose(pVnode->cq);
+  pVnode->cq = NULL;
+
+  if (pVnode->wqueue) 
+    dnodeFreeWqueue(pVnode->wqueue);
+  pVnode->wqueue = NULL;
+
+  if (pVnode->rqueue) 
+    dnodeFreeRqueue(pVnode->rqueue);
+  pVnode->rqueue = NULL;
+ 
   vnodeRelease(pVnode);
 }
 
@@ -462,7 +477,8 @@ static int32_t vnodeSaveCfg(SMDCreateVnodeMsg *pVnodeCfg) {
   if (!fp) {
     vError("vgId:%d, failed to open vnode cfg file for write, file:%s error:%s", pVnodeCfg->cfg.vgId, cfgFile,
            strerror(errno));
-    return errno;
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return terrno;
   }
 
   int32_t len = 0;
@@ -512,27 +528,30 @@ static int32_t vnodeSaveCfg(SMDCreateVnodeMsg *pVnodeCfg) {
 }
 
 static int32_t vnodeReadCfg(SVnodeObj *pVnode) {
-  char cfgFile[TSDB_FILENAME_LEN + 30] = {0};
+  cJSON  *root = NULL;
+  char   *content = NULL;
+  char    cfgFile[TSDB_FILENAME_LEN + 30] = {0};
+  int     maxLen = 1000;
+
+  terrno = TSDB_CODE_OTHERS;
   sprintf(cfgFile, "%s/vnode%d/config.json", tsVnodeDir, pVnode->vgId);
   FILE *fp = fopen(cfgFile, "r");
   if (!fp) {
-    vError("vgId:%d, failed to open vnode cfg file for read, file:%s, error:%s", pVnode->vgId,
+    vError("vgId:%d, failed to open vnode cfg file:%s to read, error:%s", pVnode->vgId,
            cfgFile, strerror(errno));
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    goto PARSE_OVER;
+  }
+
+  content = calloc(1, maxLen + 1);
+  if (content == NULL) goto PARSE_OVER;
+  int   len = fread(content, 1, maxLen, fp);
+  if (len <= 0) {
+    vError("vgId:%d, failed to read vnode cfg, content is null", pVnode->vgId);
     return errno;
   }
 
-  int   ret = TSDB_CODE_OTHERS;
-  int   maxLen = 1000;
-  char *content = calloc(1, maxLen + 1);
-  int   len = fread(content, 1, maxLen, fp);
-  if (len <= 0) {
-    free(content);
-    fclose(fp);
-    vError("vgId:%d, failed to read vnode cfg, content is null", pVnode->vgId);
-    return false;
-  }
-
-  cJSON *root = cJSON_Parse(content);
+  root = cJSON_Parse(content);
   if (root == NULL) {
     vError("vgId:%d, failed to read vnode cfg, invalid json format", pVnode->vgId);
     goto PARSE_OVER;
@@ -691,19 +710,19 @@ static int32_t vnodeReadCfg(SVnodeObj *pVnode) {
     pVnode->syncCfg.nodeInfo[i].nodePort += TSDB_PORT_SYNC;
   }
 
-  ret = 0;
+  terrno = TSDB_CODE_SUCCESS;
 
-  vPrint("vgId:%d, read vnode cfg successed, replcia:%d", pVnode->vgId, pVnode->syncCfg.replica);
+  vPrint("vgId:%d, read vnode cfg successfully, replcia:%d", pVnode->vgId, pVnode->syncCfg.replica);
   for (int32_t i = 0; i < pVnode->syncCfg.replica; i++) {
     vPrint("vgId:%d, dnode:%d, %s:%d", pVnode->vgId, pVnode->syncCfg.nodeInfo[i].nodeId,
            pVnode->syncCfg.nodeInfo[i].nodeFqdn, pVnode->syncCfg.nodeInfo[i].nodePort);
   }
 
 PARSE_OVER:
-  free(content);
+  tfree(content);
   cJSON_Delete(root);
-  fclose(fp);
-  return ret;
+  if (fp) fclose(fp);
+  return terrno;
 }
 
 static int32_t vnodeSaveVersion(SVnodeObj *pVnode) {
@@ -713,7 +732,7 @@ static int32_t vnodeSaveVersion(SVnodeObj *pVnode) {
   if (!fp) {
     vError("vgId:%d, failed to open vnode version file for write, file:%s error:%s", pVnode->vgId,
            versionFile, strerror(errno));
-    return errno;
+    return TAOS_SYSTEM_ERROR(errno); 
   }
 
   int32_t len = 0;
@@ -733,29 +752,33 @@ static int32_t vnodeSaveVersion(SVnodeObj *pVnode) {
   return 0;
 }
 
-static bool vnodeReadVersion(SVnodeObj *pVnode) {
-  char versionFile[TSDB_FILENAME_LEN + 30] = {0};
+static int32_t vnodeReadVersion(SVnodeObj *pVnode) {
+  char    versionFile[TSDB_FILENAME_LEN + 30] = {0};
+  char   *content = NULL;
+  cJSON  *root = NULL;
+  int     maxLen = 100;
+
+  terrno = TSDB_CODE_OTHERS;
   sprintf(versionFile, "%s/vnode%d/version.json", tsVnodeDir, pVnode->vgId);
   FILE *fp = fopen(versionFile, "r");
   if (!fp) {
     if (errno != ENOENT) {
       vError("vgId:%d, failed to open version file:%s error:%s", pVnode->vgId, versionFile, strerror(errno));
+      terrno = TAOS_SYSTEM_ERROR(errno);
+    } else {
+      terrno = TSDB_CODE_SUCCESS;
     }
-    return false;
+    goto PARSE_OVER;
   }
 
-  bool  ret = false;
-  int   maxLen = 100;
-  char *content = calloc(1, maxLen + 1);
+  content = calloc(1, maxLen + 1);
   int   len = fread(content, 1, maxLen, fp);
   if (len <= 0) {
-    free(content);
-    fclose(fp);
-    vPrint("vgId:%d, failed to read vnode version, content is null", pVnode->vgId);
-    return false;
+    vError("vgId:%d, failed to read vnode version, content is null", pVnode->vgId);
+    goto PARSE_OVER;
   }
 
-  cJSON *root = cJSON_Parse(content);
+  root = cJSON_Parse(content);
   if (root == NULL) {
     vError("vgId:%d, failed to read vnode version, invalid json format", pVnode->vgId);
     goto PARSE_OVER;
@@ -768,13 +791,12 @@ static bool vnodeReadVersion(SVnodeObj *pVnode) {
   }
   pVnode->version = version->valueint;
 
-  ret = true;
-
-  vPrint("vgId:%d, read vnode version succeed, version:%" PRId64, pVnode->vgId, pVnode->version);
+  terrno = TSDB_CODE_SUCCESS;
+  vPrint("vgId:%d, read vnode version successfully, version:%" PRId64, pVnode->vgId, pVnode->version);
 
 PARSE_OVER:
-  free(content);
+  tfree(content);
   cJSON_Delete(root);
-  fclose(fp);
-  return ret;
+  if(fp) fclose(fp);
+  return terrno;
 }
diff --git a/src/wal/src/walMain.c b/src/wal/src/walMain.c
index 8d92fac926..ebfc9d98bb 100644
--- a/src/wal/src/walMain.c
+++ b/src/wal/src/walMain.c
@@ -25,6 +25,7 @@
 #include "tlog.h"
 #include "tchecksum.h"
 #include "tutil.h"
+#include "taoserror.h"
 #include "twal.h"
 #include "tqueue.h"
 
@@ -56,7 +57,10 @@ static int walRemoveWalFiles(const char *path);
 
 void *walOpen(const char *path, const SWalCfg *pCfg) {
   SWal *pWal = calloc(sizeof(SWal), 1);
-  if (pWal == NULL) return NULL;
+  if (pWal == NULL) {
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return NULL;
+  }
 
   pWal->fd = -1;
   pWal->max = pCfg->wals;
@@ -75,6 +79,7 @@ void *walOpen(const char *path, const SWalCfg *pCfg) {
     walRenew(pWal);
 
   if (pWal->fd <0) {
+    terrno = TAOS_SYSTEM_ERROR(errno);
     wError("wal:%s, failed to open", path);
     pthread_mutex_destroy(&pWal->mutex);
     free(pWal);
@@ -112,9 +117,10 @@ void walClose(void *handle) {
 }
 
 int walRenew(void *handle) {
+  if (handle == NULL) return 0;
   SWal *pWal = handle;
   int   code = 0;
-  
+
   pthread_mutex_lock(&pWal->mutex);
 
   if (pWal->fd >=0) {
@@ -156,6 +162,7 @@ int walRenew(void *handle) {
 int walWrite(void *handle, SWalHead *pHead) {
   SWal *pWal = handle;
   int   code = 0;
+  if (pWal == NULL) return -1;
 
   // no wal  
   if (pWal->level == TAOS_WAL_NOLOG) return 0;
@@ -178,6 +185,7 @@ int walWrite(void *handle, SWalHead *pHead) {
 void walFsync(void *handle) {
 
   SWal *pWal = handle;
+  if (pWal == NULL) return;
 
   if (pWal->level == TAOS_WAL_FSYNC && pWal->fd >=0) {
     if (fsync(pWal->fd) < 0) {