Elasticsearch sometimes bulk update fail?

Elasticsearch version: 7.0.0

I can not reproduce the problem.

My system is frequently sync db data to Elasticsearch server through bulk method.
The proccess will do update/create/delete in bulk body.
I'm using client->bulk($params); to send the request to es server, but sometimes the document will not be updated. But the response['error'] is false.
There is no exception or error message.

Do someone has the same problem?

Does elasticsearch ensure write success?

Yes, if errors=false, the write should have been successfully persisted on the primary and current replicas.

If you do concurrent update/create/delete, you need to be careful on not submitting requests with overlapping ids. Notice that there is no guarantee that the request you send first is overwritten by the second request, unless the first request terminates before submitting the second request.