diff --git a/mysql-test/main/func_json.result b/mysql-test/main/func_json.result
index 3ad38efaf9c..6bdafb5fbd3 100644
--- a/mysql-test/main/func_json.result
+++ b/mysql-test/main/func_json.result
@@ -1646,6 +1646,17 @@ SELECT JSON_OBJECTAGG('\\', 1);
 JSON_OBJECTAGG('\\', 1)
 {"\\":1}
 #
+# MDEV-24784 JSON_ARRAYAGG charset issue
+#
+set names utf8;
+select json_arrayagg('ä'), json_objectagg(1, 'ä');
+json_arrayagg('ä')	json_objectagg(1, 'ä')
+["ä"]	{"1":"ä"}
+set names latin1;
+select json_arrayagg('ä'), json_objectagg(1, 'ä');
+json_arrayagg('ä')	json_objectagg(1, 'ä')
+["ä"]	{"1":"ä"}
+#
 # End of 10.5 tests
 #
 #
diff --git a/mysql-test/main/func_json.test b/mysql-test/main/func_json.test
index 64559d50851..4ea9dfdd628 100644
--- a/mysql-test/main/func_json.test
+++ b/mysql-test/main/func_json.test
@@ -1111,6 +1111,16 @@ SELECT JSON_OBJECTAGG('"', 1);
 SELECT JSON_OBJECTAGG('\"', 1);
 SELECT JSON_OBJECTAGG('\\', 1);
 
+--echo #
+--echo # MDEV-24784 JSON_ARRAYAGG charset issue
+--echo #
+--disable_service_connection
+set names utf8;
+select json_arrayagg('ä'), json_objectagg(1, 'ä');
+set names latin1;
+select json_arrayagg('ä'), json_objectagg(1, 'ä');
+--enable_service_connection
+
 --echo #
 --echo # End of 10.5 tests
 --echo #
diff --git a/sql/field.cc b/sql/field.cc
index 2f24a068e39..4a6b6616340 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -4689,30 +4689,6 @@ bool Field_longlong::is_max()
   single precision float
 ****************************************************************************/
 
-Field_float::Field_float(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
-                         uchar null_bit_arg,
-                         enum utype unireg_check_arg,
-                         const LEX_CSTRING *field_name_arg,
-                         decimal_digits_t dec_arg,
-                         bool zero_arg, bool unsigned_arg)
-  :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
-              unireg_check_arg, field_name_arg,
-              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
-              zero_arg, unsigned_arg)
-{
-}
-
-Field_float::Field_float(uint32 len_arg, bool maybe_null_arg,
-                         const LEX_CSTRING *field_name_arg,
-                         decimal_digits_t dec_arg)
-  :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "": 0, (uint) 0,
-              NONE, field_name_arg,
-              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
-              0, 0)
-{
-}
-
-
 int Field_float::store(const char *from,size_t len,CHARSET_INFO *cs)
 {
   int error;
@@ -4861,40 +4837,6 @@ Binlog_type_info Field_float::binlog_type_info() const
   double precision floating point numbers
 ****************************************************************************/
 
-Field_double::Field_double(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
-                           uchar null_bit_arg,
-                           enum utype unireg_check_arg,
-                           const LEX_CSTRING *field_name_arg,
-                           decimal_digits_t dec_arg,
-                           bool zero_arg, bool unsigned_arg)
-  :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
-              unireg_check_arg, field_name_arg,
-              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
-              zero_arg, unsigned_arg)
-{
-}
-
-Field_double::Field_double(uint32 len_arg, bool maybe_null_arg,
-                           const LEX_CSTRING *field_name_arg,
-                           decimal_digits_t dec_arg)
-  :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
-              NONE, field_name_arg,
-              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
-              0, 0)
-{
-}
-
-Field_double::Field_double(uint32 len_arg, bool maybe_null_arg,
-                           const LEX_CSTRING *field_name_arg,
-                           decimal_digits_t dec_arg, bool not_fixed_arg)
-  :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
-              NONE, field_name_arg,
-              (dec_arg >= FLOATING_POINT_DECIMALS ? NOT_FIXED_DEC : dec_arg),
-              0, 0)
-{
-  not_fixed= not_fixed_arg;
-}
-
 int Field_double::store(const char *from,size_t len,CHARSET_INFO *cs)
 {
   int error;
diff --git a/sql/field.h b/sql/field.h
index 3b7b201e146..1f31d6042cd 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -2121,7 +2121,7 @@ public:
 	    const LEX_CSTRING *field_name_arg,
 	    const DTCollation &collation);
   decimal_digits_t decimals() const override
-  { return is_created_from_null_item ? 0 : NOT_FIXED_DEC; }
+  { return is_created_from_null_item ? 0 : DECIMAL_NOT_SPECIFIED; }
   int  save_in_field(Field *to) override { return save_in_field_str(to); }
   bool memcpy_field_possible(const Field *from) const override
   {
@@ -2289,7 +2289,7 @@ public:
   Information_schema_numeric_attributes
     information_schema_numeric_attributes() const override
   {
-    return dec == NOT_FIXED_DEC ?
+    return dec == DECIMAL_NOT_SPECIFIED ?
                   Information_schema_numeric_attributes(field_length) :
                   Information_schema_numeric_attributes(field_length, dec);
   }
@@ -2861,15 +2861,24 @@ public:
      integers. But in all other cases we treat it as TIME_RESULT! */
 };
 
+static inline decimal_digits_t fix_dec_arg(decimal_digits_t dec_arg)
+{ return dec_arg >= FLOATING_POINT_DECIMALS ? DECIMAL_NOT_SPECIFIED : dec_arg; }
 
 class Field_float final :public Field_real {
 public:
   Field_float(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
 	      uchar null_bit_arg,
 	      enum utype unireg_check_arg, const LEX_CSTRING *field_name_arg,
-              decimal_digits_t dec_arg,bool zero_arg,bool unsigned_arg);
+              decimal_digits_t dec_arg,bool zero_arg,bool unsigned_arg)
+    :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
+                unireg_check_arg, field_name_arg,
+                fix_dec_arg(dec_arg), zero_arg, unsigned_arg)
+    { }
   Field_float(uint32 len_arg, bool maybe_null_arg,
-              const LEX_CSTRING *field_name_arg, decimal_digits_t dec_arg);
+              const LEX_CSTRING *field_name_arg, decimal_digits_t dec_arg)
+    :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "": 0, (uint) 0,
+                NONE, field_name_arg, fix_dec_arg(dec_arg), 0, 0)
+    { }
   const Type_handler *type_handler() const override
   { return &type_handler_float; }
   enum ha_base_keytype key_type() const override { return HA_KEYTYPE_FLOAT; }
@@ -2902,12 +2911,24 @@ public:
   Field_double(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
 	       uchar null_bit_arg,
 	       enum utype unireg_check_arg, const LEX_CSTRING *field_name_arg,
-	       decimal_digits_t dec_arg,bool zero_arg,bool unsigned_arg);
+	       decimal_digits_t dec_arg,bool zero_arg,bool unsigned_arg)
+    :Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
+                unireg_check_arg, field_name_arg,
+                fix_dec_arg(dec_arg), zero_arg, unsigned_arg)
+    { }
   Field_double(uint32 len_arg, bool maybe_null_arg,
-               const LEX_CSTRING *field_name_arg, decimal_digits_t dec_arg);
+               const LEX_CSTRING *field_name_arg, decimal_digits_t dec_arg)
+    :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
+                NONE, field_name_arg, fix_dec_arg(dec_arg), 0, 0)
+    { }
   Field_double(uint32 len_arg, bool maybe_null_arg,
                const LEX_CSTRING *field_name_arg,
-	       decimal_digits_t dec_arg, bool not_fixed_arg);
+	       decimal_digits_t dec_arg, bool not_fixed_arg)
+    :Field_real((uchar*) 0, len_arg, maybe_null_arg ? (uchar*) "" : 0, (uint) 0,
+                NONE, field_name_arg, fix_dec_arg(dec_arg), 0, 0)
+    {
+      not_fixed= not_fixed_arg;
+    }
   void init_for_tmp_table(Field *org_field, TABLE *new_table) override
   {
     Field::init_for_tmp_table(org_field, new_table);
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 3425f620dda..78ac38e95d2 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -3932,6 +3932,13 @@ int Arg_comparator::compare_e_json_str_basic(Item *j, Item *s)
   return MY_TEST(sortcmp(res1, res2, compare_collation()) == 0);
 }
 
+bool Item_func_json_arrayagg::fix_fields(THD *thd, Item **ref)
+{
+  bool res= Item_func_group_concat::fix_fields(thd, ref);
+  m_tmp_json.set_charset(collation.collation);
+  return res;
+}
+
 
 String *Item_func_json_arrayagg::get_str_from_item(Item *i, String *tmp)
 {
diff --git a/sql/item_jsonfunc.h b/sql/item_jsonfunc.h
index 0be796c5825..86895a7c247 100644
--- a/sql/item_jsonfunc.h
+++ b/sql/item_jsonfunc.h
@@ -669,6 +669,7 @@ public:
     static LEX_CSTRING name= {STRING_WITH_LEN("json_arrayagg(") };
     return name;
   }
+  bool fix_fields(THD *thd, Item **ref) override;
   enum Sumfunctype sum_func() const override { return JSON_ARRAYAGG_FUNC; }
 
   String* val_str(String *str) override;