diff --git a/Engine/Internal/Controllers/LCClassHookController.cs b/Engine/Internal/Controllers/LCClassHookController.cs
index 211b4b47..a43c70bc 100644
--- a/Engine/Internal/Controllers/LCClassHookController.cs
+++ b/Engine/Internal/Controllers/LCClassHookController.cs
@@ -7,6 +7,7 @@
 using Microsoft.AspNetCore.Cors;
 using LeanCloud.Storage.Internal.Object;
 using LeanCloud.Storage;
+using LeanCloud.Storage.Internal.Codec;
 
 namespace LeanCloud.Engine {
     [ApiController]
@@ -51,12 +52,17 @@ public async Task<object> Hook(string className, string hookName, JsonElement bo
 
                     LCObject result = await LCEngine.Invoke(mi, new object[] { obj }) as LCObject;
                     if (result != null) {
-                        return LCCloud.Encode(result);
+                        Dictionary<string, object> dict = LCEncoder.EncodeLCObject(result, true) as Dictionary<string, object>;
+                        dict.Remove("__type");
+                        dict.Remove("className");
+                        return dict;
                     }
                 }
                 return body;
+            } catch (LCException e) {
+                return StatusCode(400, LCEngine.ConvertException(e));
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
diff --git a/Engine/Internal/Controllers/LCFunctionController.cs b/Engine/Internal/Controllers/LCFunctionController.cs
index f64b5331..c61fb67d 100644
--- a/Engine/Internal/Controllers/LCFunctionController.cs
+++ b/Engine/Internal/Controllers/LCFunctionController.cs
@@ -21,7 +21,7 @@ public object GetFunctions() {
             try {
                 return LCEngine.GetFunctions(Request);
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
@@ -44,8 +44,10 @@ public async Task<object> Run(string funcName, JsonElement body) {
                     }
                 }
                 return body;
+            } catch (LCException e) {
+                return StatusCode(400, LCEngine.ConvertException(e));
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
@@ -68,8 +70,10 @@ public async Task<object> RPC(string funcName, JsonElement body) {
                     }
                 }
                 return body;
+            } catch (LCException e) {
+                return StatusCode(400, LCEngine.ConvertException(e));
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
diff --git a/Engine/Internal/Controllers/LCUserHookController.cs b/Engine/Internal/Controllers/LCUserHookController.cs
index 0713635e..4cf77b28 100644
--- a/Engine/Internal/Controllers/LCUserHookController.cs
+++ b/Engine/Internal/Controllers/LCUserHookController.cs
@@ -30,8 +30,10 @@ public async Task<object> HookSMSVerification(JsonElement body) {
                     return await Invoke(mi, dict);
                 }
                 return body;
+            } catch (LCException e) {
+                return StatusCode(400, LCEngine.ConvertException(e));
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
@@ -50,8 +52,10 @@ public async Task<object> HookEmailVerification(JsonElement body) {
                     return await Invoke(mi, dict);
                 }
                 return body;
+            } catch (LCException e) {
+                return StatusCode(400, LCEngine.ConvertException(e));
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
@@ -70,8 +74,10 @@ public async Task<object> HookLogin(JsonElement body) {
                     return await Invoke(mi, dict);
                 }
                 return body;
+            } catch (LCException e) {
+                return StatusCode(400, LCEngine.ConvertException(e));
             } catch (Exception e) {
-                return StatusCode(500, e.Message);
+                return StatusCode(500, LCEngine.ConvertException(e));
             }
         }
 
diff --git a/Engine/Public/LCEngine.cs b/Engine/Public/LCEngine.cs
index 8abf27f7..65aab5cf 100644
--- a/Engine/Public/LCEngine.cs
+++ b/Engine/Public/LCEngine.cs
@@ -220,14 +220,7 @@ internal static async Task<object> Invoke(MethodInfo mi, object[] parameters) {
                 }
                 return mi.Invoke(null, parameters);
             } catch (TargetInvocationException e) {
-                Exception ex = e.InnerException;
-                if (ex is LCException lcEx) {
-                    throw new Exception(JsonConvert.SerializeObject(new Dictionary<string, object> {
-                        { "code", lcEx.Code },
-                        { "message", lcEx.Message }
-                    }));
-                }
-                throw ex;
+                throw e.InnerException;
             }
         }
 
@@ -245,14 +238,7 @@ internal static async Task<object> Invoke(MethodInfo mi, object request) {
                 }
                 return mi.Invoke(null, ps);
             } catch (TargetInvocationException e) {
-                Exception ex = e.InnerException;
-                if (ex is LCException lcEx) {
-                    throw new Exception(JsonConvert.SerializeObject(new Dictionary<string, object> {
-                        { "code", lcEx.Code },
-                        { "message", lcEx.Message }
-                    }));
-                }
-                throw ex;
+                throw e.InnerException;
             }
         }
 
@@ -316,5 +302,19 @@ internal static object GetFunctions(HttpRequest request) {
                 { "result", functions }
             };
         }
+
+        internal static object ConvertException(Exception e) {
+            LCLogger.Error(e.ToString());
+            if (e is LCException lcEx) {
+                return new Dictionary<string, object> {
+                    { "code", lcEx.Code },
+                    { "error", lcEx.Message }
+                };
+            }
+            return new Dictionary<string, object> {
+                { "code", 1 },
+                { "error", e.Message }
+            };
+        }
     }
 }
diff --git a/Sample/LeanEngineApp/.leancloud/current_app_id b/Sample/LeanEngineApp/.leancloud/current_app_id
index 967a43f2..1fba4e63 100644
--- a/Sample/LeanEngineApp/.leancloud/current_app_id
+++ b/Sample/LeanEngineApp/.leancloud/current_app_id
@@ -1 +1 @@
-ikGGdRE2YcVOemAaRbgp1xGJ-gzGzoHsz
+ikGGdRE2YcVOemAaRbgp1xGJ-gzGzoHsz
\ No newline at end of file
diff --git a/Sample/LeanEngineApp/.leancloud/current_group b/Sample/LeanEngineApp/.leancloud/current_group
index c0772185..6f3439a3 100644
--- a/Sample/LeanEngineApp/.leancloud/current_group
+++ b/Sample/LeanEngineApp/.leancloud/current_group
@@ -1 +1 @@
-web
+web
\ No newline at end of file
diff --git a/Sample/LeanEngineApp/web/App.cs b/Sample/LeanEngineApp/web/App.cs
index e0164536..4d7507e6 100644
--- a/Sample/LeanEngineApp/web/App.cs
+++ b/Sample/LeanEngineApp/web/App.cs
@@ -5,9 +5,12 @@
 using System.Linq;
 using LeanCloud.Storage;
 using LeanCloud.Engine;
+using LeanCloud;
 
 namespace web {
     public class App {
+        private const string HOOK_CLASS_NAME = "TestHookClass";
+
         // Function
         [LCEngineFunction("ping")]
         public static string Ping() {
@@ -41,5 +44,56 @@ public static async Task<Dictionary<string, LCObject>> GetObjectMap() {
             ReadOnlyCollection<LCObject> todos = await query.Find();
             return todos.ToDictionary(t => t.ObjectId);
         }
+
+        [LCEngineFunction("lcexception")]
+        public static string LCException() {
+            throw new LCException(123, "Runtime exception");
+        }
+
+        [LCEngineFunction("exception")]
+        public static string Exception() {
+            throw new Exception("Hello, exception");
+        }
+
+        // Class Hook
+        [LCEngineClassHook(HOOK_CLASS_NAME, LCEngineObjectHookType.BeforeSave)]
+        public static LCObject BeforeSaveClass(LCObject obj) {
+            if (obj["score"] == null) {
+                obj["score"] = 60;
+            }
+            return obj;
+        }
+
+        [LCEngineClassHook(HOOK_CLASS_NAME, LCEngineObjectHookType.AfterSave)]
+        public static void AfterSaveClass(LCObject obj) {
+            LCLogger.Debug($"Saved {obj.ObjectId}");
+        }
+
+        [LCEngineClassHook(HOOK_CLASS_NAME, LCEngineObjectHookType.BeforeUpdate)]
+        public static LCObject BeforeUpdateClass(LCObject obj) {
+            ReadOnlyCollection<string> updatedKeys = obj.GetUpdatedKeys();
+            if (updatedKeys.Contains("score")) {
+                int score = (int) obj["score"];
+                if (score > 100) {
+                    throw new Exception($"Error score: {score}");
+                }
+            }
+            return obj;
+        }
+
+        [LCEngineClassHook(HOOK_CLASS_NAME, LCEngineObjectHookType.AfterUpdate)]
+        public static void AfterUpdateClass(LCObject obj) {
+            LCLogger.Debug($"Updated {obj.ObjectId}");
+        }
+
+        [LCEngineClassHook(HOOK_CLASS_NAME, LCEngineObjectHookType.BeforeDelete)]
+        public static void BeforeDeleteClass(LCObject obj) {
+            throw new Exception($"Cannot delete {obj.ClassName}");
+        }
+
+        [LCEngineClassHook(HOOK_CLASS_NAME, LCEngineObjectHookType.AfterDelete)]
+        public static void AfterDeleteClass(LCObject obj) {
+            LCLogger.Debug($"Deleted {obj.ObjectId}");
+        }
     }
 }
diff --git a/Sample/LeanEngineApp/web/Libs/Common.dll b/Sample/LeanEngineApp/web/Libs/Common.dll
index 5c92cb33..0be68bae 100644
Binary files a/Sample/LeanEngineApp/web/Libs/Common.dll and b/Sample/LeanEngineApp/web/Libs/Common.dll differ
diff --git a/Sample/LeanEngineApp/web/Libs/Engine.dll b/Sample/LeanEngineApp/web/Libs/Engine.dll
index 25e5976f..fba09b69 100644
Binary files a/Sample/LeanEngineApp/web/Libs/Engine.dll and b/Sample/LeanEngineApp/web/Libs/Engine.dll differ
diff --git a/Sample/LeanEngineApp/web/Libs/LC.Newtonsoft.Json.dll b/Sample/LeanEngineApp/web/Libs/LC.Newtonsoft.Json.dll
index 59ee2767..17e3d827 100644
Binary files a/Sample/LeanEngineApp/web/Libs/LC.Newtonsoft.Json.dll and b/Sample/LeanEngineApp/web/Libs/LC.Newtonsoft.Json.dll differ
diff --git a/Sample/LeanEngineApp/web/Libs/Storage.Standard.dll b/Sample/LeanEngineApp/web/Libs/Storage.Standard.dll
index f70d9875..1e5f5cfb 100644
Binary files a/Sample/LeanEngineApp/web/Libs/Storage.Standard.dll and b/Sample/LeanEngineApp/web/Libs/Storage.Standard.dll differ
diff --git a/Sample/LeanEngineApp/web/Libs/Storage.dll b/Sample/LeanEngineApp/web/Libs/Storage.dll
index 1b4b3b53..ae2c59a7 100644
Binary files a/Sample/LeanEngineApp/web/Libs/Storage.dll and b/Sample/LeanEngineApp/web/Libs/Storage.dll differ
diff --git a/Storage/Storage.AOT/Storage.AOT.csproj b/Storage/Storage.AOT/Storage.AOT.csproj
index 3a8ab48d..b42f452e 100644
--- a/Storage/Storage.AOT/Storage.AOT.csproj
+++ b/Storage/Storage.AOT/Storage.AOT.csproj
@@ -104,9 +104,6 @@
     <Compile Include="..\Storage\Public\LCHookObject.cs">
       <Link>Storage\Public\LCHookObject.cs</Link>
     </Compile>
-    <Compile Include="..\Storage\Public\LCUser.cs">
-      <Link>Storage\Public\LCUser.cs</Link>
-    </Compile>
     <Compile Include="..\Storage\Public\LCObject.cs">
       <Link>Storage\Public\LCObject.cs</Link>
     </Compile>
@@ -170,5 +167,11 @@
     <Compile Include="..\Storage\Public\Friendship\LCFollowersAndFollowees.cs">
       <Link>Storage\Public\Friendship\LCFollowersAndFollowees.cs</Link>
     </Compile>
+    <Compile Include="..\Storage\Public\User\LCUser.cs">
+      <Link>Storage\Public\User\LCUser.cs</Link>
+    </Compile>
+    <Compile Include="..\Storage\Public\User\LCUserQueryCondition.cs">
+      <Link>Storage\Public\User\LCUserQueryCondition.cs</Link>
+    </Compile>
   </ItemGroup>
 </Project>
diff --git a/Storage/Storage.Test/ClassHookTest.cs b/Storage/Storage.Test/ClassHookTest.cs
new file mode 100644
index 00000000..f0ee10f7
--- /dev/null
+++ b/Storage/Storage.Test/ClassHookTest.cs
@@ -0,0 +1,40 @@
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using System.Linq;
+using LeanCloud;
+using LeanCloud.Storage;
+
+namespace Storage.Test {
+    public class ClassHookTest : BaseTest {
+        private const string CLASS_NAME = "TestHookClass";
+
+        private LCObject obj;
+
+        [Test]
+        [Order(0)]
+        public async Task Save() {
+            obj = new LCObject(CLASS_NAME);
+            await obj.Save();
+        }
+
+        [Test]
+        [Order(10)]
+        public async Task Update() {
+            obj["score"] = 200;
+            LCException e = Assert.CatchAsync<LCException>(() => obj.Save());
+            Assert.AreEqual(e.Code, 142);
+
+            obj["score"] = 90;
+            await obj.Save();
+        }
+
+        [Test]
+        [Order(20)]
+        public void Delete() {
+            LCException e = Assert.CatchAsync<LCException>(() => obj.Delete());
+            Assert.AreEqual(e.Code, 142);
+        }
+    }
+}
diff --git a/Storage/Storage.Test/CloudTest.cs b/Storage/Storage.Test/CloudTest.cs
index 37bcfef2..f4e600a3 100644
--- a/Storage/Storage.Test/CloudTest.cs
+++ b/Storage/Storage.Test/CloudTest.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using System.Linq;
+using LeanCloud;
 using LeanCloud.Storage;
 
 namespace Storage.Test {
@@ -58,5 +59,19 @@ public async Task GetObjectMap() {
                 Assert.AreEqual(kv.Key, obj.ObjectId);
             }
         }
+
+        [Test]
+        public void CatchLCException() {
+            LCException ex = Assert.CatchAsync<LCException>(() => LCCloud.Run("lcexception"));
+            Assert.AreEqual(ex.Code, 123);
+            Assert.AreEqual(ex.Message, "Runtime exception");
+        }
+
+        [Test]
+        public void CatchException() {
+            LCException ex = Assert.CatchAsync<LCException>(() => LCCloud.Run("exception"));
+            Assert.AreEqual(ex.Code, 1);
+            Assert.AreEqual(ex.Message, "Hello, exception");
+        }
     }
 }
diff --git a/Storage/Storage.Test/UserTest.cs b/Storage/Storage.Test/UserTest.cs
index d869fe59..ac652d52 100644
--- a/Storage/Storage.Test/UserTest.cs
+++ b/Storage/Storage.Test/UserTest.cs
@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using System.Text;
+using System.Collections.ObjectModel;
 using LeanCloud;
 using LeanCloud.Storage;
 using LC.Newtonsoft.Json;
@@ -298,6 +299,27 @@ public async Task AuthData() {
             }
         }
 
+        [Test]
+        [Order(18)]
+        public async Task QueryUser() {
+            LCUser anoymous1 = await LCUser.LoginAnonymously();
+
+            string nickname = anoymous1.ObjectId;
+            anoymous1["nickname"] = nickname;
+            await anoymous1.Save();
+
+            await LCUser.LoginAnonymously();
+
+            LCUserQueryCondition condition = new LCUserQueryCondition();
+            condition.WhereEqualTo("nickname", nickname);
+            ReadOnlyCollection<LCUser> users = await LCUser.StrictlyFind(condition);
+
+            Assert.Greater(users.Count, 0);
+            foreach (LCUser user in users) {
+                Assert.AreEqual(user.ObjectId, anoymous1.ObjectId);
+            }
+        }
+
         private string GetTestEmail() {
             return $"{TestPhone}@leancloud.rocks";
         }
diff --git a/Storage/Storage/Internal/Query/LCCompositionalCondition.cs b/Storage/Storage/Internal/Query/LCCompositionalCondition.cs
index f5c8318d..087bbf9b 100644
--- a/Storage/Storage/Internal/Query/LCCompositionalCondition.cs
+++ b/Storage/Storage/Internal/Query/LCCompositionalCondition.cs
@@ -8,9 +8,9 @@ public class LCCompositionalCondition : ILCQueryCondition {
         public const string And = "$and";
         public const string Or = "$or";
 
-        readonly string composition;
+        protected string composition;
 
-        List<ILCQueryCondition> conditionList;
+        protected List<ILCQueryCondition> conditionList;
 
         List<string> orderByList;
         HashSet<string> includes;
@@ -217,8 +217,9 @@ public Dictionary<string, object> BuildParams() {
                 { "skip", Skip },
                 { "limit", Limit }
             };
-            if (conditionList != null && conditionList.Count > 0) {
-                dict["where"] = JsonConvert.SerializeObject(Encode());
+            string where = BuildWhere();
+            if (!string.IsNullOrEmpty(where)) {
+                dict["where"] = where;
             }
             string order = BuildOrders();
             if (!string.IsNullOrEmpty(order)) {
diff --git a/Storage/Storage/Public/LCCloud.cs b/Storage/Storage/Public/LCCloud.cs
index f90557eb..1115020f 100644
--- a/Storage/Storage/Public/LCCloud.cs
+++ b/Storage/Storage/Public/LCCloud.cs
@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using LeanCloud.Common;
 using LeanCloud.Storage.Internal.Codec;
-using LeanCloud.Storage.Internal.Object;
 
 namespace LeanCloud.Storage {
     /// <summary>
diff --git a/Storage/Storage/Public/LCUser.cs b/Storage/Storage/Public/User/LCUser.cs
similarity index 96%
rename from Storage/Storage/Public/LCUser.cs
rename to Storage/Storage/Public/User/LCUser.cs
index cc29036b..06c36613 100644
--- a/Storage/Storage/Public/LCUser.cs
+++ b/Storage/Storage/Public/User/LCUser.cs
@@ -2,6 +2,7 @@
 using System.Threading.Tasks;
 using System.Collections;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using LeanCloud.Common;
 using LeanCloud.Storage.Internal.Object;
 
@@ -778,5 +779,30 @@ public static LCUser GenerateUser(LCObjectData objectData) {
             user.Merge(objectData);
             return user;
         }
+
+        public static async Task<ReadOnlyCollection<LCUser>> StrictlyFind(LCUserQueryCondition condition) {
+            if (condition == null) {
+                throw new ArgumentNullException(nameof(condition));
+            }
+
+            string path = "users/strictlyQuery";
+            Dictionary<string, object> dict = new Dictionary<string, object> {};
+            string where = condition.BuildWhere();
+            if (!string.IsNullOrEmpty(where)) {
+                dict["where"] = where;
+            }
+            
+            Dictionary<string, object> response = await LCCore.HttpClient.Get<Dictionary<string, object>>(path,
+                queryParams: dict);
+            List<object> results = response["results"] as List<object>;
+            List<LCUser> users = new List<LCUser>();
+            foreach (object item in results) {
+                LCUser user = Create(CLASS_NAME) as LCUser;
+                LCObjectData objectData = LCObjectData.Decode(item as Dictionary<string, object>);
+                user.Merge(objectData);
+                users.Add(user);
+            }
+            return users.AsReadOnly();
+        }
     }
 }
diff --git a/Storage/Storage/Public/User/LCUserQueryCondition.cs b/Storage/Storage/Public/User/LCUserQueryCondition.cs
new file mode 100644
index 00000000..a06a4554
--- /dev/null
+++ b/Storage/Storage/Public/User/LCUserQueryCondition.cs
@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using LeanCloud.Storage.Internal.Query;
+
+namespace LeanCloud.Storage {
+    public class LCUserQueryCondition : LCCompositionalCondition {
+        public new int Skip {
+            get { throw new NotImplementedException(); }
+            set { throw new NotImplementedException(); }
+        }
+
+        public new int Limit {
+            get { throw new NotImplementedException(); }
+            set { throw new NotImplementedException(); }
+        }
+
+        public new void WhereMatchesQuery<K>(string key, LCQuery<K> query) where K : LCObject {
+            throw new NotImplementedException();
+        }
+
+        public LCUserQueryCondition() {
+            composition = And;
+        }
+
+        public new Dictionary<string, object> BuildParams() {
+            Dictionary<string, object> dict = base.BuildParams();
+            // LCUserQueryCondition 不支持下面的参数
+            dict.Remove("skip");
+            dict.Remove("limit");
+            return dict;
+        }
+    }
+}
diff --git a/Storage/Storage/Storage.csproj b/Storage/Storage/Storage.csproj
index fd1ae5c3..15a2a9fc 100644
--- a/Storage/Storage/Storage.csproj
+++ b/Storage/Storage/Storage.csproj
@@ -20,6 +20,7 @@
     <Folder Include="Public\Friendship\" />
     <Folder Include="Public\Status\" />
     <Folder Include="Public\Search\" />
+    <Folder Include="Public\User\" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\Common\Common\Common.csproj">
@@ -29,5 +30,6 @@
     <None Remove="Public\Friendship\" />
     <None Remove="Public\Status\" />
     <None Remove="Public\Search\" />
+    <None Remove="Public\User\" />
   </ItemGroup>
 </Project>