mongodb查询并插入数据报错 400 请求报错 

从数据库里查询符合条件的记录并插入到另一个数据库中，没执行完就终止了，求大神帮助，出现信息：

Wed Dec 18 21:56:15.667 [conn1] { $err: "BSONObj size: 0 (0x00000000) is invalid

. Size must be between 0 and 16793600(16MB) First element: EOO", code: 10334 }

Wed Dec 18 21:56:15.668 [conn1] getmore test.microblogs cursorid:135126098217621

ntoreturn:0 keyUpdates:0 exception: BSONObj size: 0 (0x00000000) is invalid. Si

ze must be between 0 and 16793600(16MB) First element: EOO code:10334 numYields:

4 locks(micros) r:8920037 nreturned:0 reslen:20 8894ms

Wed Dec 18 21:56:15.703 [conn1] end connection 127.0.0.1:49270 (0 connections no

w open)