diff --git a/module/custom/model.php b/module/custom/model.php
index b229e57a1c..4c31d66833 100644
--- a/module/custom/model.php
+++ b/module/custom/model.php
@@ -579,13 +579,20 @@ class customModel extends model
 
         $data = fixer::input('post')->get();
         $requiredFields = array();
-        if(!empty($data->requiredFields))
+        if(!empty($systemFields))
         {
-            foreach($data->requiredFields as $method => $fields)
+            foreach($systemFields as $method => $fields)
             {
                 $systemField = $this->config->$moduleName->$method->requiredFields;
 
-                $fields = join(',', $fields);
+                /* Keep the original required fields when the fields is empty. */
+                if(!isset($data->requiredFields[$method]))
+                {
+                    $requiredFields[$method]['requiredFields'] = $systemField;
+                    continue;
+                }
+
+                $fields = join(',', $data->requiredFields[$method]);
                 foreach(explode(',', $systemField) as $field)
                 {
                     $field = trim($field);
@@ -597,7 +604,6 @@ class customModel extends model
         }
 
         $this->loadModel('setting');
-        $this->setting->deleteItems("owner=system&module={$moduleName}");
         $this->setting->setItems("system.{$moduleName}", $requiredFields);
     }
 
diff --git a/module/programplan/lang/zh-cn.php b/module/programplan/lang/zh-cn.php
index e7be31fde9..7d6fa7f818 100644
--- a/module/programplan/lang/zh-cn.php
+++ b/module/programplan/lang/zh-cn.php
@@ -65,6 +65,6 @@ $lang->programplan->stageCustom->task = '显示任务';
 $lang->programplan->error                  = new stdclass();
 $lang->programplan->error->percentNumber   = '"工作量比例"必须为数字';
 $lang->programplan->error->planFinishSmall = '"计划完成时间"必须大于"计划开始时间"';
-$lang->programplan->error->percentOver     = '"工作量占比"累计不应当超过100%';
+$lang->programplan->error->percentOver     = '工作量占比累计不应当超过100%';
 $lang->programplan->error->createdTask     = '已分解任务,不可添加子阶段';
 $lang->programplan->error->parentWorkload  = '子阶段的工作量之和不能大于父阶段的工作量:%s';
diff --git a/module/programplan/lang/zh-tw.php b/module/programplan/lang/zh-tw.php
index 5a33dd569f..d9115a18d8 100644
--- a/module/programplan/lang/zh-tw.php
+++ b/module/programplan/lang/zh-tw.php
@@ -65,6 +65,6 @@ $lang->programplan->stageCustom->task = '顯示任務';
 $lang->programplan->error                  = new stdclass();
 $lang->programplan->error->percentNumber   = '"工作量比例"必須為數字';
 $lang->programplan->error->planFinishSmall = '"計劃完成時間"必須大於"計劃開始時間"';
-$lang->programplan->error->percentOver     = '"工作量占比"累計不應當超過100%';
+$lang->programplan->error->percentOver     = '工作量占比累計不應當超過100%';
 $lang->programplan->error->createdTask     = '已分解任務,不可添加子階段';
 $lang->programplan->error->parentWorkload  = '子階段的工作量之和不能大於父階段的工作量:%s';
diff --git a/module/project/lang/zh-cn.php b/module/project/lang/zh-cn.php
index 457ad2790f..261ed10e40 100644
--- a/module/project/lang/zh-cn.php
+++ b/module/project/lang/zh-cn.php
@@ -265,7 +265,7 @@ $lang->project->byPeriod            = '按时间段';
 $lang->project->byUser              = '按用户';
 $lang->project->noProject           = "暂时没有{$lang->executionCommon}。";
 $lang->project->noMembers           = '暂时没有团队成员。';
-$lang->project->workloadTotal       = "工作量比例累计不应当超过100, 当前产品下的工作量之和为:%s";
+$lang->project->workloadTotal       = "工作量占比累计不应当超过100%, 当前产品下的工作量之和为:%s";
 $lang->project->linkPRJStoryTip     = "(关联{$lang->SRCommon}来源于项目下所关联的{$lang->SRCommon})";
 $lang->project->linkAllStoryTip     = "(项目下还未关联{$lang->SRCommon}，可直接关联该迭代/阶段所关联产品的{$lang->SRCommon})";