diff --git a/source/client/test/timezoneTest.cpp b/source/client/test/timezoneTest.cpp
index b8f68f62dd..8b95dd148b 100644
--- a/source/client/test/timezoneTest.cpp
+++ b/source/client/test/timezoneTest.cpp
@@ -177,9 +177,41 @@ TEST(timezoneCase, alter_timezone_Test) {
   execQuery(pConn, "alter local 'timezone Asia/Kolkata'");
   check_timezone(pConn, "show local variables", "Asia/Kolkata");
 
+  execQuery(pConn, "alter local 'timezone Asia/Shanghai'");
+  check_timezone(pConn, "show local variables", "Asia/Shanghai");
+
   execQueryFail(pConn, "alter dnode 1 'timezone Asia/Kolkata'");
 }
 
+char *tz_test[] = {
+    "2023-09-16 17:00:00+",
+    "2023-09-16 17:00:00+8:",
+    "2023-09-16 17:00:00+:30",
+    "2023-09-16 17:00:00+:-30",
+    "2023-09-16 17:00:00++:-30",
+    "2023-09-16 17:00:00+:",
+    "2023-09-16 17:00:00+8f:",
+    "2023-09-16 17:00:00+080:",
+    "2023-09-16 17:00:00+080",
+    "2023-09-16 17:00:00+a",
+    "2023-09-16 17:00:00+09:",
+    "2023-09-16 17:00:00+09:a",
+    "2023-09-16 17:00:00+09:abc",
+    "2023-09-16 17:00:00+09:001",
+};
+
+void do_insert_failed(){
+  TAOS* pConn = getConnWithGlobalOption("UTC-8");
+
+  for (unsigned int i = 0; i < sizeof (tz_test) / sizeof (tz_test[0]); ++i){
+    char sql[1024] = {0};
+    (void)snprintf(sql, sizeof(sql), "insert into db1.ctb1 values('%s', '%s', 1)", tz_test[i], tz_test[i]);
+
+    execQueryFail(pConn, sql);
+  }
+  taos_close(pConn);
+}
+
 struct insert_params
 {
   const char *tz;
@@ -227,7 +259,7 @@ TEST(timezoneCase, insert_with_timezone_Test) {
   execQuery(pConn1, "create table db1.ctb1 using db1.stb tags(\"2023-09-16 17:00:00+05:00\", \"2023-09-16 17:00:00\", 1)");
   execQuery(pConn1, "create table db1.ctb2 using db1.stb tags(1732178775000, 1732178775000, 1)");
   execQuery(pConn1, "insert into db1.ntb values(1732178775133, 1732178775133, 1)");
-  execQuery(pConn1, "insert into db1.ctb1 values(1732178775133, 1732178775133, 1)");
+  execQuery(pConn1, "insert into db1.ctb1 values(1732178775133, 1732178775133, 1)"); //2024-11-21 10:46:15.133+02:00
   execQuery(pConn1, "insert into db1.ctb2 values(1732178775133, 1732178775133, 1)");
 
   /*
@@ -251,6 +283,7 @@ TEST(timezoneCase, insert_with_timezone_Test) {
     do_select(params2[i]);
   }
 
+  do_insert_failed();
   /*
    * 4. test NULL timezone, use default timezone UTC-8
    */
@@ -284,7 +317,7 @@ TEST(timezoneCase, func_timezone_Test) {
   execQuery(pConn, "insert into db1.ntb values(1704142800000, '2024-01-01 23:00:00', 1)");   // 2024-01-01 23:00:00+0200
 
   // test timezone
-  check_sql_result(pConn, "select timezone()", "UTC-test (UTC, +0200)");
+  check_sql_result(pConn, "select timezone()", "UTC-2 (UTC, +0200)");
 
   // test timetruncate
   check_sql_result(pConn, "select TO_ISO8601(TIMETRUNCATE('2024-01-01 23:00:00', 1d, 0))", "2024-01-01T02:00:00.000+0200");
diff --git a/source/common/src/ttime.c b/source/common/src/ttime.c
index a5da856e4f..681660bfb7 100644
--- a/source/common/src/ttime.c
+++ b/source/common/src/ttime.c
@@ -130,8 +130,15 @@ int32_t parseFraction(char* str, char** end, int32_t timePrec, int64_t* pFractio
   TAOS_RETURN(TSDB_CODE_SUCCESS);
 }
 
+#define PARSE(str,len,result) \
+  if (len > 2 || len < 1) {\
+    TAOS_RETURN(TSDB_CODE_INVALID_PARA);\
+  }\
+  result = strnatoi(str, len);
+
 int32_t parseTimezone(char* str, int64_t* tzOffset) {
   int64_t hour = 0;
+  int64_t minute = 0;
 
   int32_t i = 0;
   if (str[i] != '+' && str[i] != '-') {
@@ -152,30 +159,24 @@ int32_t parseTimezone(char* str, int64_t* tzOffset) {
 
   char* sep = strchr(&str[i], ':');
   if (sep != NULL) {
-    int32_t len = (int32_t)(sep - &str[i]);
+    int32_t hourSize = (int32_t)(sep - &str[i]);
+    PARSE(&str[i], hourSize, hour);
 
-    hour = strnatoi(&str[i], len);
-    i += len + 1;
+    i += hourSize + 1;
+    size_t minSize = strlen(&str[i]);
+    PARSE(&str[i], minSize, minute);
+    if (minute > 59 || minute < 0) {
+      TAOS_RETURN(TSDB_CODE_INVALID_PARA);
+    }
   } else {
-    hour = strnatoi(&str[i], 2);
-    i += 2;
+    size_t hourSize = strlen(&str[i]);
+    PARSE(&str[i], hourSize, hour)
   }
 
   if (hour > 13 || hour < 0) {
     TAOS_RETURN(TSDB_CODE_INVALID_PARA);
   }
 
-  // return error if there're illegal charaters after min(2 Digits)
-  char* minStr = &str[i];
-  if (minStr[1] != '\0' && minStr[2] != '\0') {
-    TAOS_RETURN(TSDB_CODE_INVALID_PARA);
-  }
-
-  int64_t minute = strnatoi(&str[i], 2);
-  if (minute > 59 || minute < 0) {
-    TAOS_RETURN(TSDB_CODE_INVALID_PARA);
-  }
-
   if (str[0] == '+') {
     *tzOffset = -(hour * 3600 + minute * 60);
   } else {
diff --git a/source/os/src/osString.c b/source/os/src/osString.c
index 4506248eec..d8109bab0c 100644
--- a/source/os/src/osString.c
+++ b/source/os/src/osString.c
@@ -238,16 +238,16 @@ iconv_t taosAcquireConv(int32_t *idx, ConvType type, void* charsetCxt) {
     charsetCxt = tsCharsetCxt;
   }
   SConvInfo *info = (SConvInfo *)charsetCxt;
-  if (info->gConvMaxNum[type] <= 0) {
+  if (info == NULL) {
     *idx = -1;
     if (type == M2C) {
-      iconv_t c = iconv_open(DEFAULT_UNICODE_ENCODEC, info->charset);
+      iconv_t c = iconv_open(DEFAULT_UNICODE_ENCODEC, "UTF-8");
       if ((iconv_t)-1 == c) {
         terrno = TAOS_SYSTEM_ERROR(errno);
       }
       return c;
     } else {
-      iconv_t c = iconv_open(info->charset, DEFAULT_UNICODE_ENCODEC);
+      iconv_t c = iconv_open("UTF-8", DEFAULT_UNICODE_ENCODEC);
       if ((iconv_t)-1 == c) {
         terrno = TAOS_SYSTEM_ERROR(errno);
       }