diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 89da3c5640c6523d4d2a816b8ae0293310c5830a..380ce651332135c4fc9fab112e8ac66a23b722c8 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -195,6 +195,9 @@ TAOS *taos_connect_internal(const char *ip, const char *user, const char *pass,
     tsem_wait(&pSql->rspSem);
 
     pSql->pTscObj->pClusterInfo = (SClusterInfo *)tscAcquireClusterInfo(pSql->pTscObj->clusterId);
+    if (pSql->pTscObj->pClusterInfo == NULL) {
+      assert(pSql->res.code != TSDB_CODE_SUCCESS);
+    } 
     if (pSql->res.code != TSDB_CODE_SUCCESS) {
       terrno = pSql->res.code;
       if (terrno ==TSDB_CODE_RPC_FQDN_ERROR) {
diff --git a/src/client/src/tscSystem.c b/src/client/src/tscSystem.c
index f6614fdb79f18b70cadc2351edc8e402e95bf41e..bc8d0db4858bff7f38fdfb2b463d583bcac06fc2 100644
--- a/src/client/src/tscSystem.c
+++ b/src/client/src/tscSystem.c
@@ -133,8 +133,11 @@ void tscClusterInfoDestroy(SClusterInfo *pObj) {
 
 void *tscAcquireClusterInfo(const char *clusterId) {
   pthread_mutex_lock(&clusterMutex);
-  
   size_t len = strlen(clusterId);
+  if (len == 0) {
+    pthread_mutex_unlock(&clusterMutex);
+    return NULL;
+  }
   SClusterInfo *pObj   = NULL;
   SClusterInfo **ppObj = taosHashGet(tscClusterMap, clusterId, len); 
   if (ppObj == NULL || *ppObj == NULL) {