diff --git a/paddle/gserver/evaluators/Evaluator.cpp b/paddle/gserver/evaluators/Evaluator.cpp
index 8fce8df8a3b0e52cc8af4d6848d2ba797757e8cd..6c1c2f62be273cf4855621d28da74befec8f259f 100644
--- a/paddle/gserver/evaluators/Evaluator.cpp
+++ b/paddle/gserver/evaluators/Evaluator.cpp
@@ -781,9 +781,7 @@ real PrecisionRecallEvaluator::getValue(const std::string& name,
   paddle::str::split(name, '.', &buffers);
   auto it = this->values_.find(buffers[buffers.size() - 1]);
   if (it == this->values_.end()) {  // not found
-    if (err != nullptr) {
-      *err = Error("No such key %s", name.c_str());
-    }
+    *err = Error("No such key %s", name.c_str());
     return .0f;
   }
 
@@ -792,10 +790,6 @@ real PrecisionRecallEvaluator::getValue(const std::string& name,
 
 std::string PrecisionRecallEvaluator::getType(const std::string& name,
                                               Error* err) const {
-  Error localErr;
-  if (err == nullptr) {
-    err = &localErr;
-  }
   this->getValue(name, err);
   if (!err->isOK()) {
     return "";
diff --git a/paddle/gserver/evaluators/Evaluator.h b/paddle/gserver/evaluators/Evaluator.h
index eb19e6f4dde5d90e8479b7bd2d78d9bcb61e84dd..6a122704ea34aea0a78d757e2235561faece69d6 100644
--- a/paddle/gserver/evaluators/Evaluator.h
+++ b/paddle/gserver/evaluators/Evaluator.h
@@ -141,16 +141,13 @@ public:
    * @brief getValue will return the current evaluate value of one field.
    *
    * @param name: The field name of current evaluator.
-   * @param err [out]: The error state. nullptr means don't care.
+   * @param err [out]: The error state.
    *
    * @return The evaluate value(metric).
    */
-  virtual real getValue(const std::string& name,
-                        paddle::Error* err = nullptr) const {
+  virtual real getValue(const std::string& name, paddle::Error* err) const {
     if (name != config_.name()) {
-      if (err != nullptr) {
-        *err = paddle::Error("no such name of evaluator %s", name.c_str());
-      }
+      *err = paddle::Error("no such name of evaluator %s", name.c_str());
       return .0f;
     }
     return this->getValueImpl();
@@ -168,8 +165,8 @@ public:
    * @return the evaluator type string.
    */
   virtual std::string getType(const std::string& name,
-                              paddle::Error* err = nullptr) const {
-    if (name != config_.name() && err != nullptr) {
+                              paddle::Error* err) const {
+    if (name != config_.name()) {
       *err = paddle::Error("no such name of evaluator %s", name.c_str());
       return std::string();
     }
@@ -212,15 +209,11 @@ public:
   void getNames(std::vector<std::string>* names) {}
 
   real getValue(const std::string& name, Error* err) const {
-    if (err != nullptr) {
-      *err = Error("Not implemented");
-    }
+    *err = Error("Not implemented");
     return .0f;
   }
   std::string getType(const std::string& name, Error* err) const {
-    if (err != nullptr) {
-      *err = Error("Not implemented");
-    }
+    *err = Error("Not implemented");
     return "";
   }
 };
diff --git a/paddle/gserver/gradientmachines/NeuralNetwork.cpp b/paddle/gserver/gradientmachines/NeuralNetwork.cpp
index 4d2bdf0dc992da32659de0f18f685fbcbbeb5656..273a9111c35a21c01f0cd8d283ecc6eaa4ef0c61 100644
--- a/paddle/gserver/gradientmachines/NeuralNetwork.cpp
+++ b/paddle/gserver/gradientmachines/NeuralNetwork.cpp
@@ -391,7 +391,7 @@ private:
         return callback(eval);
       }
     }
-    if (err != nullptr) *err = Error("No such key %s", name.c_str());
+    *err = Error("No such key %s", name.c_str());
     return T();
   }
 };