title: Aggregation:com.mongodb.MongoCommandException: Command failed with error 16436:
body: <p>I am using mongodb and wanted to store my log data in the form array in the document. While reading from the collection 
  I am using aggregation pipe line. When I tired to use the query in Mongo Booster, the Query is working fine but it was giving
  the following exception when I tried to use it by Java Program.</p>
  
  <p>Details:
    --> db.version() - 3.2.7
    --> mongo-java_driver: 3.2.2</p>
  
  <pre><code>Query in Mongo Booster:
  =======================
  db.logCollection.aggregate({$unwind:'$logList'},{ $sort : {'logList.log.timestamp': -1} },{ $match:{'logList.log.userId': "100100"}},{ $group: {_id: null, logList: {$push: '$logList'}}},{ $project: {  _id: 0,logList: {log:{timestamp: 1,operation:1}}}}).pretty()
  
   Query: using Java
   =================
  
   DBObject unwindField = new BasicDBObject("$unwind", "$logList");
    DBObject groupFields = new BasicDBObject("_id", null);         
    groupFields.put("logList", new BasicDBObject("$push","$logList")); 
    DBObject group = new BasicDBObject("$group", groupFields);
    DB logDB = mongoClient.getDB("logdb");
    DBCollection collection=logDB.getCollection(collectionName);      
    DBObject skipFields = new BasicDBObject("$skip",skip);
    DBObject limitFields = new BasicDBObject("$limit",limit);
    Iterable&lt;DBObject&gt; results =null;
    try { 
      results= collection.aggregate(unwindField, sortField,searchField,skipFields,limitFields,group,projectFields).results();
      } catch (Exception e) {
       log.error("readLogsFromCollection() Failed");
  
     }
  
  Exception:
  ==========
  com.mongodb.MongoCommandException: Command failed with error 16436: 'Unrecognized pipeline stage name: 'logList.log.timestamp' on server localhost:27017.
  The full response is { "ok" : 0.0, "errmsg" : "Unrecognized pipeline stage name: 'logList.log.timestamp'", "code" : 16436 }
  
  Input Document:
  ================
  
  {
      "logList" : [
          {
              "log" : {
                  "acctId" : "0",
                  "info1" : {
                      "itemName" : "-",
                      "value" : "-"
                  },
                  "errorCode" : "",
                  "internalInformation" : "",
                  "kind" : "Infomation",
                  "groupId" : "0",
                  "logId" : "G1_1",
                  "operation" : "startDiscovery",
                  "result" : "normal",
                  "userId" : "100100",
                  "timestamp" : "1470980265729"
              }
          }
      ]
  }
  </code></pre>
  
  <p>Could any body tell me what might be the problem, I read the issue is with version, but I Used mongo-java_driver-3.3 also but no use.</p>
  
  <p>Thanks in advance.</p>