diff --git a/broker/src/main/java/com/xiaoleilu/loServer/pojos/InputCreateGroup.java b/broker/src/main/java/com/xiaoleilu/loServer/pojos/InputCreateGroup.java
index ebb49cc4..92bdff99 100755
--- a/broker/src/main/java/com/xiaoleilu/loServer/pojos/InputCreateGroup.java
+++ b/broker/src/main/java/com/xiaoleilu/loServer/pojos/InputCreateGroup.java
@@ -58,12 +58,16 @@ public class InputCreateGroup extends InputGroupBase {
 
         WFCMessage.CreateGroupRequest.Builder createGroupReqBuilder = WFCMessage.CreateGroupRequest.newBuilder();
         createGroupReqBuilder.setGroup(groupBuilder);
-        for (Integer line : to_lines
-             ) {
-            createGroupReqBuilder.addToLine(line);
+        if (to_lines != null) {
+            for (Integer line : to_lines
+            ) {
+                createGroupReqBuilder.addToLine(line);
+            }
         }
 
-        createGroupReqBuilder.setNotifyContent(notify_message.toProtoMessageContent());
+        if (notify_message != null) {
+            createGroupReqBuilder.setNotifyContent(notify_message.toProtoMessageContent());
+        }
         return createGroupReqBuilder.build();
     }
 
diff --git a/broker/src/main/java/io/moquette/persistence/MemoryMessagesStore.java b/broker/src/main/java/io/moquette/persistence/MemoryMessagesStore.java
index d2221124..aae763c7 100755
--- a/broker/src/main/java/io/moquette/persistence/MemoryMessagesStore.java
+++ b/broker/src/main/java/io/moquette/persistence/MemoryMessagesStore.java
@@ -583,6 +583,8 @@ public class MemoryMessagesStore implements IMessagesStore {
         long dt = System.currentTimeMillis();
         if (StringUtil.isNullOrEmpty(groupInfo.getTargetId())) {
             groupId = getShortUUID();
+        } else {
+            groupId = groupInfo.getTargetId();
         }
         groupInfo = groupInfo.toBuilder()
             .setTargetId(groupId)