diff --git a/README.md b/README.md
index 84f9ccfa66e37fb173a3bd3d32116251de838107..b88fdbed537854ad5b7fd5e85e29eba738d25dcc 100644
--- a/README.md
+++ b/README.md
@@ -99,9 +99,9 @@ It is because of the shoulders of these open source projects that the birth of t
 ### Get Help
 1. Submit an issue
 1. Subscribe the mail list : https://dolphinscheduler.apache.org/en-us/docs/development/subscribe.html.  then send mail to dev@dolphinscheduler.apache.org
+1. Slack channel: [![Slack Status](https://img.shields.io/badge/slack-join_chat-white.svg?logo=slack&style=social)](https://join.slack.com/share/zt-do3gvfhj-UUhrAX2GxkVX_~JJt1jpKA)
 1. Contact WeChat(dailidong66). This is just for Mandarin(CN) discussion.
 
 ### License
 Please refer to [LICENSE](https://github.com/apache/incubator-dolphinscheduler/blob/dev/LICENSE) file.
 
-
diff --git a/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/ExecutorService.java b/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/ExecutorService.java
index 1aab0953daea4980904cfa304d20dd9b65b5afd6..611d3ea7f992f71a76b1532b7a19f888c8acce88 100644
--- a/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/ExecutorService.java
+++ b/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/ExecutorService.java
@@ -124,14 +124,12 @@ public class ExecutorService extends BaseService{
             return result;
         }
 
-        // check master server exists
-        List<Server> masterServers = monitorService.getServerListFromZK(true);
-
-
-        if (masterServers.size() == 0) {
-            putMsg(result, Status.MASTER_NOT_EXISTS);
+        // check master exists
+        if (!checkMasterExists(result)) {
             return result;
         }
+
+
         /**
          * create command
          */
@@ -152,6 +150,22 @@ public class ExecutorService extends BaseService{
         return result;
     }
 
+    /**
+     * check whether master exists
+     * @param result result
+     * @return master exists return true , otherwise return false
+     */
+    private boolean checkMasterExists(Map<String, Object> result) {
+        // check master server exists
+        List<Server> masterServers = monitorService.getServerListFromZK(true);
+
+        // no master
+        if (masterServers.size() == 0) {
+            putMsg(result, Status.MASTER_NOT_EXISTS);
+            return false;
+        }
+        return true;
+    }
 
 
     /**
@@ -195,6 +209,12 @@ public class ExecutorService extends BaseService{
             return checkResult;
         }
 
+        // check master exists
+        if (!checkMasterExists(result)) {
+            return result;
+        }
+
+
         ProcessInstance processInstance = processService.findProcessInstanceDetailById(processInstanceId);
         if (processInstance == null) {
             putMsg(result, Status.PROCESS_INSTANCE_NOT_EXIST, processInstanceId);