diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo.Abp.Json.SystemTextJson.csproj b/framework/src/Volo.Abp.Json.SystemTextJson/Volo.Abp.Json.SystemTextJson.csproj
index e7551a0e42..08ea7d91e6 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo.Abp.Json.SystemTextJson.csproj
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo.Abp.Json.SystemTextJson.csproj
@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <AssemblyName>Volo.Abp.Json.SystemTextJson</AssemblyName>
         <PackageId>Volo.Abp.Json.SystemTextJson</PackageId>
         <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonSerializer.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonSerializer.cs
index 8313f6ee99..6f433ce918 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonSerializer.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonSerializer.cs
@@ -22,12 +22,12 @@ public class AbpSystemTextJsonSerializer : IJsonSerializer, ITransientDependency
 
     public T Deserialize<T>(string jsonString, bool camelCase = true)
     {
-        return JsonSerializer.Deserialize<T>(jsonString, CreateJsonSerializerOptions(camelCase));
+        return JsonSerializer.Deserialize<T>(jsonString, CreateJsonSerializerOptions(camelCase))!;
     }
 
     public object Deserialize(Type type, string jsonString, bool camelCase = true)
     {
-        return JsonSerializer.Deserialize(jsonString, type, CreateJsonSerializerOptions(camelCase));
+        return JsonSerializer.Deserialize(jsonString, type, CreateJsonSerializerOptions(camelCase))!;
     }
 
     private static readonly ConcurrentDictionary<object, JsonSerializerOptions> JsonSerializerOptionsCache =
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpNullableStringToGuidConverter.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpNullableStringToGuidConverter.cs
index c80e5aa9a5..973faca170 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpNullableStringToGuidConverter.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpNullableStringToGuidConverter.cs
@@ -6,7 +6,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpNullableStringToGuidConverter : JsonConverter<Guid?>
 {
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public override Guid? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToBooleanConverter.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToBooleanConverter.cs
index e704f2ceb0..443150e41a 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToBooleanConverter.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToBooleanConverter.cs
@@ -8,7 +8,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpStringToBooleanConverter : JsonConverter<bool>
 {
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public override bool Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumConverter.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumConverter.cs
index 6b7f32807e..d1e8fc555d 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumConverter.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumConverter.cs
@@ -9,9 +9,9 @@ public class AbpStringToEnumConverter<T> : JsonConverter<T>
 {
     private readonly JsonStringEnumConverter _innerJsonStringEnumConverter;
 
-    private JsonSerializerOptions _readJsonSerializerOptions;
+    private JsonSerializerOptions? _readJsonSerializerOptions;
 
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public AbpStringToEnumConverter()
         : this(namingPolicy: null, allowIntegerValues: true)
@@ -19,7 +19,7 @@ public class AbpStringToEnumConverter<T> : JsonConverter<T>
 
     }
 
-    public AbpStringToEnumConverter(JsonNamingPolicy namingPolicy = null, bool allowIntegerValues = true)
+    public AbpStringToEnumConverter(JsonNamingPolicy? namingPolicy = null, bool allowIntegerValues = true)
     {
         _innerJsonStringEnumConverter = new JsonStringEnumConverter(namingPolicy, allowIntegerValues);
     }
@@ -50,11 +50,11 @@ public class AbpStringToEnumConverter<T> : JsonConverter<T>
 
     public override T ReadAsPropertyName(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
-        return (T)Enum.Parse(typeToConvert, reader.GetString());
+        return (T)Enum.Parse(typeToConvert, reader.GetString()!);
     }
 
     public override void WriteAsPropertyName(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
     {
-        writer.WritePropertyName(Enum.GetName(typeof(T), value));
+        writer.WritePropertyName(Enum.GetName(typeof(T), value)!);
     }
 }
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumFactory.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumFactory.cs
index d94d85e546..bda510e5dc 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumFactory.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToEnumFactory.cs
@@ -7,7 +7,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpStringToEnumFactory : JsonConverterFactory
 {
-    private readonly JsonNamingPolicy _namingPolicy;
+    private readonly JsonNamingPolicy? _namingPolicy;
     private readonly bool _allowIntegerValues;
 
     public AbpStringToEnumFactory()
@@ -16,7 +16,7 @@ public class AbpStringToEnumFactory : JsonConverterFactory
 
     }
 
-    public AbpStringToEnumFactory(JsonNamingPolicy namingPolicy, bool allowIntegerValues)
+    public AbpStringToEnumFactory(JsonNamingPolicy? namingPolicy, bool allowIntegerValues)
     {
         _namingPolicy = namingPolicy;
         _allowIntegerValues = allowIntegerValues;
@@ -33,7 +33,7 @@ public class AbpStringToEnumFactory : JsonConverterFactory
             typeof(AbpStringToEnumConverter<>).MakeGenericType(typeToConvert),
             BindingFlags.Instance | BindingFlags.Public,
             binder: null,
-            new object[] { _namingPolicy, _allowIntegerValues },
+            new object?[] { _namingPolicy, _allowIntegerValues },
             culture: null)!;
     }
 }
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToGuidConverter.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToGuidConverter.cs
index 586e4462cf..5cb1062c0c 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToGuidConverter.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/AbpStringToGuidConverter.cs
@@ -6,7 +6,7 @@ namespace Volo.Abp.Json.SystemTextJson.JsonConverters;
 
 public class AbpStringToGuidConverter : JsonConverter<Guid>
 {
-    private JsonSerializerOptions _writeJsonSerializerOptions;
+    private JsonSerializerOptions? _writeJsonSerializerOptions;
 
     public override Guid Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/ObjectToInferredTypesConverter.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/ObjectToInferredTypesConverter.cs
index b1bffc95b8..bf017d041e 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/ObjectToInferredTypesConverter.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/JsonConverters/ObjectToInferredTypesConverter.cs
@@ -12,16 +12,16 @@ public class ObjectToInferredTypesConverter : JsonConverter<object>
     public override object Read(
         ref Utf8JsonReader reader,
         Type typeToConvert,
-        JsonSerializerOptions options) => reader.TokenType switch
-        {
-            JsonTokenType.True => true,
-            JsonTokenType.False => false,
-            JsonTokenType.Number when reader.TryGetInt64(out long l) => l,
-            JsonTokenType.Number => reader.GetDouble(),
-            JsonTokenType.String when reader.TryGetDateTime(out DateTime datetime) => datetime,
-            JsonTokenType.String => reader.GetString(),
-            _ => JsonDocument.ParseValue(ref reader).RootElement.Clone()
-        };
+        JsonSerializerOptions options) => (reader.TokenType switch
+    {
+        JsonTokenType.True => true,
+        JsonTokenType.False => false,
+        JsonTokenType.Number when reader.TryGetInt64(out long l) => l,
+        JsonTokenType.Number => reader.GetDouble(),
+        JsonTokenType.String when reader.TryGetDateTime(out DateTime datetime) => datetime,
+        JsonTokenType.String => reader.GetString(),
+        _ => JsonDocument.ParseValue(ref reader).RootElement.Clone()
+    })!;
 
     public override void Write(
         Utf8JsonWriter writer,
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpDateTimeConverterModifier.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpDateTimeConverterModifier.cs
index a691423cf3..ba19ccfa29 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpDateTimeConverterModifier.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpDateTimeConverterModifier.cs
@@ -10,7 +10,7 @@ namespace Volo.Abp.Json.SystemTextJson.Modifiers;
 
 public class AbpDateTimeConverterModifier
 {
-    private IServiceProvider _serviceProvider;
+    private IServiceProvider _serviceProvider = default!;
 
     public Action<JsonTypeInfo> CreateModifyAction(IServiceProvider serviceProvider)
     {
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIgnorePropertiesModifiers.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIgnorePropertiesModifiers.cs
index 27a50395bf..7c1db739d1 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIgnorePropertiesModifiers.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIgnorePropertiesModifiers.cs
@@ -9,7 +9,7 @@ namespace Volo.Abp.Json.SystemTextJson.Modifiers;
 public class AbpIgnorePropertiesModifiers<TClass, TProperty>
     where TClass : class
 {
-    private Expression<Func<TClass, TProperty>> _propertySelector;
+    private Expression<Func<TClass, TProperty>> _propertySelector = default!;
 
     public Action<JsonTypeInfo> CreateModifyAction(Expression<Func<TClass, TProperty>> propertySelector)
     {
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeExtraPropertiesModifiers.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeExtraPropertiesModifiers.cs
index f4a97e0e9d..c7fadc47db 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeExtraPropertiesModifiers.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeExtraPropertiesModifiers.cs
@@ -17,7 +17,7 @@ public static class AbpIncludeExtraPropertiesModifiers
                 .Where(x => x.AttributeProvider is MemberInfo)
                 .FirstOrDefault(x =>
                     x.PropertyType == typeof(ExtraPropertyDictionary) &&
-                    x.AttributeProvider.As<MemberInfo>().Name == nameof(ExtensibleObject.ExtraProperties) &&
+                    x.AttributeProvider!.As<MemberInfo>().Name == nameof(ExtensibleObject.ExtraProperties) &&
                     x.Set == null);
 
             if (propertyJsonInfo != null)
diff --git a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeNonPublicPropertiesModifiers.cs b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeNonPublicPropertiesModifiers.cs
index 4669ddc666..cc13db8d0c 100644
--- a/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeNonPublicPropertiesModifiers.cs
+++ b/framework/src/Volo.Abp.Json.SystemTextJson/Volo/Abp/Json/SystemTextJson/Modifiers/AbpIncludeNonPublicPropertiesModifiers.cs
@@ -9,7 +9,7 @@ namespace Volo.Abp.Json.SystemTextJson.Modifiers;
 public class AbpIncludeNonPublicPropertiesModifiers<TClass, TProperty>
     where TClass : class
 {
-    private Expression<Func<TClass, TProperty>> _propertySelector;
+    private Expression<Func<TClass, TProperty>> _propertySelector = default!;
 
     public Action<JsonTypeInfo> CreateModifyAction(Expression<Func<TClass, TProperty>> propertySelector)
     {