diff --git a/crates/oxide_builtins/src/object.rs b/crates/oxide_builtins/src/object.rs
index 139c4ea..655af79 100644
--- a/crates/oxide_builtins/src/object.rs
+++ b/crates/oxide_builtins/src/object.rs
@@ -252,12 +252,23 @@ pub fn object_define_property<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResul
     let get_field = own_field(vm, desc, get_si);
     let set_field = own_field(vm, desc, set_si);
     let writable_field = own_field(vm, desc, writable_si);
+
+    let existing_pos = {
+        let obj = unsafe { &*obj_ptr };
+        vm.get_own_property_slot(obj, si)
+    };
+    let existing_meta = existing_pos.and_then(|pos| {
+        let obj = unsafe { &*obj_ptr };
+        obj.prop_meta_at(pos)
+    });
+
+    // 修改已有属性时缺省字段回填现有值，仅定义新属性时缺省才为 false。
     let enumerable = own_field(vm, desc, enumerable_si)
         .map(oxide_runtime_api::to_boolean)
-        .unwrap_or(false);
+        .unwrap_or_else(|| existing_meta.map(|m| m.attributes.enumerable()).unwrap_or(false));
     let configurable = own_field(vm, desc, configurable_si)
         .map(oxide_runtime_api::to_boolean)
-        .unwrap_or(false);
+        .unwrap_or_else(|| existing_meta.map(|m| m.attributes.configurable()).unwrap_or(false));
 
     let has_data = value_field.is_some() || writable_field.is_some();
     let has_accessor = get_field.is_some() || set_field.is_some();
@@ -268,14 +279,6 @@ pub fn object_define_property<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResul
         ));
     }
 
-    let existing_pos = {
-        let obj = unsafe { &*obj_ptr };
-        vm.get_own_property_slot(obj, si)
-    };
-    let existing_meta = existing_pos.and_then(|pos| {
-        let obj = unsafe { &*obj_ptr };
-        obj.prop_meta_at(pos)
-    });
     let existing_value = existing_pos.map_or(JsValue::undefined(), |pos| {
         let obj = unsafe { &*obj_ptr };
         obj.get_prop_at(pos)
@@ -301,11 +304,9 @@ pub fn object_define_property<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResul
                 "accessor descriptor get/set must be callable or undefined",
             ));
         }
-        if vm
-            .define_accessor_property(obj, si, get, set, PropAttributes::new(false, enumerable, configurable))
-            .is_err()
+        if let Err(e) = vm.define_accessor_property(obj, si, get, set, PropAttributes::new(false, enumerable, configurable))
         {
-            return NativeResult::Err(crate::error::create_type_error(vm, "Cannot define property"));
+            return NativeResult::Err(crate::error::create_type_error(vm, &e));
         }
     } else if has_data {
         let value = if existing_pos.is_some() {
@@ -320,24 +321,18 @@ pub fn object_define_property<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResul
         } else {
             writable_field.map(oxide_runtime_api::to_boolean).unwrap_or(false)
         };
-        if vm
-            .define_data_property(obj, si, value, PropAttributes::new(writable, enumerable, configurable))
-            .is_err()
-        {
-            return NativeResult::Err(crate::error::create_type_error(vm, "Cannot define property"));
+        if let Err(e) = vm.define_data_property(obj, si, value, PropAttributes::new(writable, enumerable, configurable)) {
+            return NativeResult::Err(crate::error::create_type_error(vm, &e));
         }
     } else {
         if existing_pos.is_none() {
-            if vm
-                .define_data_property(
-                    obj,
-                    si,
-                    JsValue::undefined(),
-                    PropAttributes::new(false, enumerable, configurable),
-                )
-                .is_err()
-            {
-                return NativeResult::Err(crate::error::create_type_error(vm, "Cannot define property"));
+            if let Err(e) = vm.define_data_property(
+                obj,
+                si,
+                JsValue::undefined(),
+                PropAttributes::new(false, enumerable, configurable),
+            ) {
+                return NativeResult::Err(crate::error::create_type_error(vm, &e));
             }
             return NativeResult::Ok(obj_val);
         }
@@ -347,13 +342,11 @@ pub fn object_define_property<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResul
         if is_accessor {
             let get = existing_meta.map(|m| m.get).unwrap_or(JsValue::undefined());
             let set = existing_meta.map(|m| m.set).unwrap_or(JsValue::undefined());
-            if vm.define_accessor_property(obj, si, get, set, attrs).is_err() {
-                return NativeResult::Err(crate::error::create_type_error(vm, "Cannot define property"));
-            }
-        } else {
-            if vm.define_data_property(obj, si, existing_value, attrs).is_err() {
-                return NativeResult::Err(crate::error::create_type_error(vm, "Cannot define property"));
+            if let Err(e) = vm.define_accessor_property(obj, si, get, set, attrs) {
+                return NativeResult::Err(crate::error::create_type_error(vm, &e));
             }
+        } else if let Err(e) = vm.define_data_property(obj, si, existing_value, attrs) {
+            return NativeResult::Err(crate::error::create_type_error(vm, &e));
         }
     }
     NativeResult::Ok(obj_val)
diff --git a/crates/oxide_vm/src/dispatch/misc.rs b/crates/oxide_vm/src/dispatch/misc.rs
index b48bd16..cdf3eee 100644
--- a/crates/oxide_vm/src/dispatch/misc.rs
+++ b/crates/oxide_vm/src/dispatch/misc.rs
@@ -157,12 +157,18 @@ impl Vm {
 
         // length：实参个数，可写、不可枚举、可配置。
         let length_si = self.kernel_core.perm_interner().intern("length").0;
-        self.define_data_property(obj, length_si, JsValue::int(count as i32), PropAttributes::new(true, false, true))?;
+        if let Err(msg) =
+            self.define_data_property(obj, length_si, JsValue::int(count as i32), PropAttributes::new(true, false, true))
+        {
+            return self.raise_error_kind("TypeError", &msg);
+        }
 
         // callee：当前执行函数，可写、不可枚举、可配置（严格模式应抛 TypeError，未支持）。
         let callee_si = self.kernel_core.perm_interner().intern("callee").0;
         let callee = self.current_callee().unwrap_or(JsValue::undefined());
-        self.define_data_property(obj, callee_si, callee, PropAttributes::new(true, false, true))?;
+        if let Err(msg) = self.define_data_property(obj, callee_si, callee, PropAttributes::new(true, false, true)) {
+            return self.raise_error_kind("TypeError", &msg);
+        }
 
         self.regs[rd] = JsValue::from_js_object(obj_ptr);
         Ok(())
diff --git a/crates/oxide_vm/src/vm_dispatch_ctrl.rs b/crates/oxide_vm/src/vm_dispatch_ctrl.rs
index 70f032a..4fd7068 100644
--- a/crates/oxide_vm/src/vm_dispatch_ctrl.rs
+++ b/crates/oxide_vm/src/vm_dispatch_ctrl.rs
@@ -118,7 +118,10 @@ impl Vm {
         } else {
             setter
         };
-        self.define_accessor_property(obj, prop_name_si, get, set, PropAttributes::DEFAULT_DATA)
+        match self.define_accessor_property(obj, prop_name_si, get, set, PropAttributes::DEFAULT_DATA) {
+            Ok(()) => Ok(()),
+            Err(msg) => self.raise_error_kind("TypeError", &msg),
+        }
     }
 
     pub(crate) fn dispatch_return(&mut self, rd: usize) -> Result<Option<JsValue>, String> {
diff --git a/crates/oxide_vm/src/vm_props.rs b/crates/oxide_vm/src/vm_props.rs
index 3dab249..3946fe1 100644
--- a/crates/oxide_vm/src/vm_props.rs
+++ b/crates/oxide_vm/src/vm_props.rs
@@ -346,18 +346,18 @@ impl Vm {
         if let Some(current) = obj.prop_meta_at(pos) {
             if !current.attributes.configurable() {
                 if current.is_accessor {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
                 if current.attributes.enumerable() != attributes.enumerable() {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
                 if !current.attributes.writable()
                     && (attributes.writable() || !coercion::same_value(obj.get_prop_at(pos), val))
                 {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
                 if current.attributes.configurable() != attributes.configurable() {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
             }
         }
@@ -399,7 +399,7 @@ impl Vm {
                     || current.get != get
                     || current.set != set)
             {
-                return self.raise_type_error("cannot redefine non-configurable property");
+                return Err("cannot redefine non-configurable property".to_string());
             }
         }
         obj.set_prop_storage(pos, JsValue::undefined());
@@ -422,28 +422,28 @@ impl Vm {
     ) -> Result<(), String> {
         let pos = index as usize;
         if pos > oxide_types::object::MAX_DENSE_PROPS {
-            return self.raise_type_error("array index out of dense range");
+            return Err("array index out of dense range".to_string());
         }
         let pos = pos as u32;
         if let Some(current) = obj.prop_meta_at(pos) {
             if !current.attributes.configurable() {
                 if current.is_accessor != is_accessor {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
                 if current.attributes.enumerable() != attributes.enumerable() {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
                 if current.attributes.configurable() != attributes.configurable() {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
                 if is_accessor {
                     if current.get != get || current.set != set {
-                        return self.raise_type_error("cannot redefine non-configurable property");
+                        return Err("cannot redefine non-configurable property".to_string());
                     }
                 } else if !current.attributes.writable()
                     && (attributes.writable() || !coercion::same_value(obj.get_prop_at(pos), val))
                 {
-                    return self.raise_type_error("cannot redefine non-configurable property");
+                    return Err("cannot redefine non-configurable property".to_string());
                 }
             }
         }