diff --git a/framework/src/Volo.Abp.Json/Volo/Abp/Json/AbpHybridJsonSerializer.cs b/framework/src/Volo.Abp.Json/Volo/Abp/Json/AbpHybridJsonSerializer.cs
index 560d6baa36..923123b107 100644
--- a/framework/src/Volo.Abp.Json/Volo/Abp/Json/AbpHybridJsonSerializer.cs
+++ b/framework/src/Volo.Abp.Json/Volo/Abp/Json/AbpHybridJsonSerializer.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using JetBrains.Annotations;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Volo.Abp.DependencyInjection;
@@ -18,17 +19,19 @@ namespace Volo.Abp.Json
             ServiceScopeFactory = serviceScopeFactory;
         }
 
-        public string Serialize(object obj, bool camelCase = true, bool indented = false)
+        public string Serialize([CanBeNull]object obj, bool camelCase = true, bool indented = false)
         {
             using (var scope = ServiceScopeFactory.CreateScope())
             {
-                var serializerProvider = GetSerializerProvider(scope.ServiceProvider, obj.GetType());
+                var serializerProvider = GetSerializerProvider(scope.ServiceProvider, obj?.GetType());
                 return serializerProvider.Serialize(obj, camelCase, indented);
             }
         }
 
-        public T Deserialize<T>(string jsonString, bool camelCase = true)
+        public T Deserialize<T>([NotNull]string jsonString, bool camelCase = true)
         {
+            Check.NotNull(jsonString, nameof(jsonString));
+
             using (var scope = ServiceScopeFactory.CreateScope())
             {
                 var serializerProvider = GetSerializerProvider(scope.ServiceProvider, typeof(T));
@@ -36,8 +39,10 @@ namespace Volo.Abp.Json
             }
         }
 
-        public object Deserialize(Type type, string jsonString, bool camelCase = true)
+        public object Deserialize(Type type, [NotNull]string jsonString, bool camelCase = true)
         {
+            Check.NotNull(jsonString, nameof(jsonString));
+
             using (var scope = ServiceScopeFactory.CreateScope())
             {
                 var serializerProvider = GetSerializerProvider(scope.ServiceProvider, type);
@@ -45,7 +50,7 @@ namespace Volo.Abp.Json
             }
         }
 
-        protected virtual IJsonSerializerProvider GetSerializerProvider(IServiceProvider serviceProvider, Type type)
+        protected virtual IJsonSerializerProvider GetSerializerProvider(IServiceProvider serviceProvider, [CanBeNull]Type type)
         {
             foreach (var providerType in Options.Providers.Reverse())
             {
diff --git a/framework/src/Volo.Abp.Json/Volo/Abp/Json/IJsonSerializerProvider.cs b/framework/src/Volo.Abp.Json/Volo/Abp/Json/IJsonSerializerProvider.cs
index f844dc5fd0..fa974b5aeb 100644
--- a/framework/src/Volo.Abp.Json/Volo/Abp/Json/IJsonSerializerProvider.cs
+++ b/framework/src/Volo.Abp.Json/Volo/Abp/Json/IJsonSerializerProvider.cs
@@ -1,10 +1,11 @@
 using System;
+using JetBrains.Annotations;
 
 namespace Volo.Abp.Json
 {
     public interface IJsonSerializerProvider
     {
-        bool CanHandle(Type type);
+        bool CanHandle([CanBeNull]Type type);
 
         string Serialize(object obj, bool camelCase = true, bool indented = false);
 
diff --git a/framework/src/Volo.Abp.Json/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonUnsupportedTypeMatcher.cs b/framework/src/Volo.Abp.Json/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonUnsupportedTypeMatcher.cs
index 2beea42c68..9004a0c404 100644
--- a/framework/src/Volo.Abp.Json/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonUnsupportedTypeMatcher.cs
+++ b/framework/src/Volo.Abp.Json/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonUnsupportedTypeMatcher.cs
@@ -1,4 +1,5 @@
 using System;
+using JetBrains.Annotations;
 using Microsoft.Extensions.Options;
 using Volo.Abp.DependencyInjection;
 
@@ -13,7 +14,7 @@ namespace Volo.Abp.Json.SystemTextJson
             Options = options.Value;
         }
 
-        public virtual bool Match(Type type)
+        public virtual bool Match([CanBeNull]Type type)
         {
             return Options.UnsupportedTypes.Contains(type);
         }