diff --git a/source/dnode/vnode/src/tsdb/tsdbMergeTree.c b/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
index 099bde5897..9938c073ff 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
@@ -833,7 +833,8 @@ bool tLDataIterNextRow(SLDataIter *pIter, const char *idStr) {
   int32_t     code = 0;
   int32_t     iBlockL = pIter->iSttBlk;
   SBlockData *pBlockData = NULL;
-
+  terrno = 0;
+  
   // no qualified last file block in current file, no need to fetch row
   if (pIter->pSttBlk == NULL) {
     return false;
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead2.c b/source/dnode/vnode/src/tsdb/tsdbRead2.c
index 0572df2922..9a9c74a3a0 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead2.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead2.c
@@ -3598,6 +3598,7 @@ static int32_t buildBlockFromFiles(STsdbReader* pReader) {
 
   if (pBlockIter->numOfBlocks == 0) {
     // let's try to extract data from stt files.
+    terrno = 0;
     ERetrieveType type = doReadDataFromSttFiles(pReader);
     if (type == TSDB_READ_RETURN) {
       return terrno;