diff --git a/src/TensorFlowNET.Core/Gradients/ops.gradient_function_mapping.cs b/src/TensorFlowNET.Core/Gradients/ops.gradient_function_mapping.cs
index 4891fcbb..b479ba0b 100644
--- a/src/TensorFlowNET.Core/Gradients/ops.gradient_function_mapping.cs
+++ b/src/TensorFlowNET.Core/Gradients/ops.gradient_function_mapping.cs
@@ -26,31 +26,8 @@ namespace Tensorflow
     {
         static Dictionary<string, Func<Operation, Tensor[], Tensor[]>> gradientFunctions = null;
 
-        /// <summary>
-        /// Regiter new gradient function
-        /// </summary>
-        /// <param name="name">operation type</param>
-        /// <param name="func">function delegate</param>
-        public static void RegisterGradientFunction(string name, Func<Operation, Tensor[], Tensor[]> func)
+        private static void RegisterFromAssembly()
         {
-            if(gradientFunctions == null)
-                gradientFunctions = new Dictionary<string, Func<Operation, Tensor[], Tensor[]>>();
-
-            gradientFunctions[name] = func;
-        }
-
-        public static void RegisterNoGradientFunction(string name)
-        {
-            if (gradientFunctions == null)
-                gradientFunctions = new Dictionary<string, Func<Operation, Tensor[], Tensor[]>>();
-
-            gradientFunctions[name] = null;
-        }
-
-        public static Func<Operation, Tensor[], Tensor[]> get_gradient_function(Operation op)
-        {
-            if (op.inputs == null) return null;
-
             if (gradientFunctions == null)
             {
                 gradientFunctions = new Dictionary<string, Func<Operation, Tensor[], Tensor[]>>();
@@ -62,7 +39,8 @@ namespace Tensorflow
 
                 foreach (var g in gradGroups)
                 {
-                    var methods = g.GetMethods().Where(x => x.GetCustomAttribute<RegisterGradient>() != null)
+                    var methods = g.GetMethods()
+                        .Where(x => x.GetCustomAttribute<RegisterGradient>() != null)
                         .ToArray();
 
                     foreach (var m in methods)
@@ -78,13 +56,40 @@ namespace Tensorflow
                     }
 
                     // REGISTER_NO_GRADIENT_OP
-                    methods = g.GetMethods().Where(x => x.GetCustomAttribute<RegisterNoGradient>() != null)
+                    methods = g.GetMethods()
+                        .Where(x => x.GetCustomAttribute<RegisterNoGradient>() != null)
                         .ToArray();
 
                     foreach (var m in methods)
                         RegisterNoGradientFunction(m.GetCustomAttribute<RegisterNoGradient>().Name);
                 }
             }
+        }
+
+        /// <summary>
+        /// Regiter new gradient function
+        /// </summary>
+        /// <param name="name">operation type</param>
+        /// <param name="func">function delegate</param>
+        public static void RegisterGradientFunction(string name, Func<Operation, Tensor[], Tensor[]> func)
+        {
+            RegisterFromAssembly();
+
+            gradientFunctions[name] = func;
+        }
+
+        public static void RegisterNoGradientFunction(string name)
+        {
+            RegisterFromAssembly();
+
+            gradientFunctions[name] = null;
+        }
+
+        public static Func<Operation, Tensor[], Tensor[]> get_gradient_function(Operation op)
+        {
+            if (op.inputs == null) return null;
+
+            RegisterFromAssembly();
 
             if (!gradientFunctions.ContainsKey(op.type))
                 throw new LookupError($"can't get graident function through get_gradient_function {op.type}");
diff --git a/src/TensorFlowNET.Core/TensorFlow.Binding.csproj b/src/TensorFlowNET.Core/TensorFlow.Binding.csproj
index 3cb7ccb2..a2958d16 100644
--- a/src/TensorFlowNET.Core/TensorFlow.Binding.csproj
+++ b/src/TensorFlowNET.Core/TensorFlow.Binding.csproj
@@ -65,7 +65,7 @@ https://tensorflownet.readthedocs.io</Description>
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Google.Protobuf" Version="3.10.1" />
+    <PackageReference Include="Google.Protobuf" Version="3.11.2" />
     <PackageReference Include="NumSharp" Version="0.20.4" />
   </ItemGroup>