diff --git a/src/connector/odbc/src/todbc.c b/src/connector/odbc/src/todbc.c
index af8d3e99c2..e1af13f6d4 100644
--- a/src/connector/odbc/src/todbc.c
+++ b/src/connector/odbc/src/todbc.c
@@ -193,6 +193,22 @@ do {                                                                    \
       SET_ERROR(sql, "22001", TSDB_CODE_ODBC_CONV_TRUNC, "");           \
       return SQL_ERROR;                                                 \
     } break;                                                            \
+    case TSDB_CONV_SRC_TOO_LARGE: {                                     \
+      SET_ERROR(sql, "22001", TSDB_CODE_ODBC_CONV_SRC_TOO_LARGE, "");   \
+      return SQL_ERROR;                                                 \
+    } break;                                                            \
+    case TSDB_CONV_SRC_BAD_SEQ: {                                       \
+      SET_ERROR(sql, "22001", TSDB_CODE_ODBC_CONV_SRC_BAD_SEQ, "");     \
+      return SQL_ERROR;                                                 \
+    } break;                                                            \
+    case TSDB_CONV_SRC_INCOMPLETE: {                                    \
+      SET_ERROR(sql, "22001", TSDB_CODE_ODBC_CONV_SRC_INCOMPLETE, "");  \
+      return SQL_ERROR;                                                 \
+    } break;                                                            \
+    case TSDB_CONV_SRC_GENERAL: {                                       \
+      SET_ERROR(sql, "22001", TSDB_CODE_ODBC_CONV_SRC_GENERAL, "");     \
+      return SQL_ERROR;                                                 \
+    } break;                                                            \
     case TSDB_CONV_BAD_CHAR: {                                          \
       SET_ERROR(sql, "22001", TSDB_CODE_ODBC_CONV_TRUNC, "");           \
       return SQL_ERROR;                                                 \
diff --git a/src/connector/odbc/src/todbc_conv.c b/src/connector/odbc/src/todbc_conv.c
index 978c6c2d84..9c0f19764c 100644
--- a/src/connector/odbc/src/todbc_conv.c
+++ b/src/connector/odbc/src/todbc_conv.c
@@ -35,6 +35,10 @@ const char* tsdb_conv_code_str(TSDB_CONV_CODE code) {
     case TSDB_CONV_CHAR_NOT_TS:        return "TSDB_CONV_CHAR_NOT_TS";
     case TSDB_CONV_NOT_VALID_TS:       return "TSDB_CONV_NOT_VALID_TS";
     case TSDB_CONV_GENERAL:            return "TSDB_CONV_GENERAL";
+    case TSDB_CONV_SRC_TOO_LARGE:      return "TSDB_CONV_SRC_TOO_LARGE";
+    case TSDB_CONV_SRC_BAD_SEQ:        return "TSDB_CONV_SRC_BAD_SEQ";
+    case TSDB_CONV_SRC_INCOMPLETE:     return "TSDB_CONV_SRC_INCOMPLETE";
+    case TSDB_CONV_SRC_GENERAL:        return "TSDB_CONV_SRC_GENERAL";
     case TSDB_CONV_BAD_CHAR:           return "TSDB_CONV_BAD_CHAR";
     default: return "UNKNOWN";
   };
@@ -408,7 +412,7 @@ tsdb_conv_t* tsdb_conv_open(const char *from_enc, const char *to_enc) {
   pthread_once(&once, once_init);
   tsdb_conv_t *cnv = (tsdb_conv_t*)calloc(1, sizeof(*cnv));
   if (!cnv) return NULL;
-  if (strcmp(from_enc, to_enc)==0) {
+  if (strcmp(from_enc, to_enc)==0 && 0) {
     cnv->cnv = (iconv_t)-1;
     cnv->direct = 1;
     return cnv;
@@ -619,7 +623,20 @@ TSDB_CONV_CODE tsdb_conv(tsdb_conv_t *cnv, stack_buffer_t *buffer, const char *s
   size_t r = iconv(cnv->cnv, (char**)&src, &slen, &buf, &blen);
   do {
     if (r==(size_t)-1) {
-      code = TSDB_CONV_BAD_CHAR;
+      switch(errno) {
+        case E2BIG: {
+          code = TSDB_CONV_SRC_TOO_LARGE;
+        } break;
+        case EILSEQ: {
+          code = TSDB_CONV_SRC_BAD_SEQ;
+        } break;
+        case EINVAL: {
+          code = TSDB_CONV_SRC_INCOMPLETE;
+        } break;
+        default: {
+          code = TSDB_CONV_SRC_GENERAL;
+        } break;
+      }
       break;
     }
     if (slen) {
diff --git a/src/connector/odbc/src/todbc_conv.h b/src/connector/odbc/src/todbc_conv.h
index 8dcaca0d02..2941f3e496 100644
--- a/src/connector/odbc/src/todbc_conv.h
+++ b/src/connector/odbc/src/todbc_conv.h
@@ -33,6 +33,10 @@ typedef enum {
   TSDB_CONV_NOT_VALID_TS,
   TSDB_CONV_GENERAL,
   TSDB_CONV_BAD_CHAR,
+  TSDB_CONV_SRC_TOO_LARGE,
+  TSDB_CONV_SRC_BAD_SEQ,
+  TSDB_CONV_SRC_INCOMPLETE,
+  TSDB_CONV_SRC_GENERAL,
 } TSDB_CONV_CODE;
 
 const char* tsdb_conv_code_str(TSDB_CONV_CODE code);
diff --git a/src/inc/taoserror.h b/src/inc/taoserror.h
index d15d162d6c..50b3fb3bfc 100644
--- a/src/inc/taoserror.h
+++ b/src/inc/taoserror.h
@@ -380,6 +380,10 @@ TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_CONNECTION_BUSY,         0, 0x210e, "connection
 TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_BAD_CONNSTR,             0, 0x210f, "bad connection string")
 TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_BAD_ARG,                 0, 0x2110, "bad argument")
 TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_CONV_NOT_VALID_TS,       0, 0x2111, "not a valid timestamp")
+TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_CONV_SRC_TOO_LARGE,      0, 0x2112, "src too large")
+TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_CONV_SRC_BAD_SEQ,        0, 0x2113, "src bad sequence")
+TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_CONV_SRC_INCOMPLETE,     0, 0x2114, "src incomplete")
+TAOS_DEFINE_ERROR(TSDB_CODE_ODBC_CONV_SRC_GENERAL,        0, 0x2115, "src general")
 
 
 #ifdef TAOS_ERROR_C