KeyError: 'found' on Elastic2DocManager when syncing data from MongoDB

[fjaweihyafei]

I sync the database with Mongo-Connector using Elastic2DocManager:

mongo-connector -m localhost:27017 -t localhost:9200 -d elastic2_doc_manager
After seeing some update on docs.deleted of mongodb_meta on Elastic Search:

health status index uuid pri rep docs.count docs.deleted store.size pri.store.size
yellow open mongodb_meta 3wd6OjTT6tD3f6ZGezZw 5 1 1337173 8372 192.9mb 192.9mb
mongo-connector stops working with below error:

During handling of the above exception, another exception occurred:
...
Exception in thread Thread-1:
Traceback (most recent call last):
File "c:\programdata\anaconda3\lib\threading.py", line 916, in _bootstrap_inner
self.run()
File "c:\programdata\anaconda3\lib\site-packages\mongo_connector\doc_managers\elastic2_doc_manager.py", line 150, in run
self._docman.send_buffered_operations()
File "c:\programdata\anaconda3\lib\site-packages\mongo_connector\doc_managers\elastic2_doc_manager.py", line 482, in send_buffered_operations
action_buffer = self.BulkBuffer.get_buffer()
File "c:\programdata\anaconda3\lib\site-packages\mongo_connector\doc_managers\elastic2_doc_manager.py", line 696, in get_buffer
self.update_sources()
File "c:\programdata\anaconda3\lib\site-packages\mongo_connector\util.py", line 35, in wrapped
return f(*args, **kwargs)
File "c:\programdata\anaconda3\lib\site-packages\mongo_connector\doc_managers\elastic2_doc_manager.py", line 628, in update_sources
if ES_doc['found']:
KeyError: 'found'