Mongodb: Document size of 29344731 is larger than maximum of 16777216 When we are upgrading AEM 6.1 instance with mongo (Mongo version: 2.6 ) to AEM 6.3  with mongo (Mongo version: 3.2) we are facing the exception.


  org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore
  Background operation failed: org.bson.BsonSerializationException:
  Document size of 29344731 is larger than maximum of 16777216.


How DocumentNodestore exceeds its limit? 
Is there anyway to resolve the issue?
Is revision garbage collection will reduce the DocumentNodeStore size?
As per MongoDB BOL here The maximum BSON document size is 16 megabytes.

The maximum document size helps ensure that a single document cannot use excessive amount of RAM or, during transmission, excessive amount of bandwidth. To store documents larger than the maximum size, MongoDB provides the GridFS API.

GridFS is a specification for storing and retrieving files that exceed the BSON-document size limit of 16 MB.

For your further ref here and here