Getting an exception in ES 2.3.1

Elastic Stack Elasticsearch
1

I've read quite a bit about this error(IllegalIndexShardsStateException) on the Internet, but still not able to do anything about it.
How can I ensure this error doesn't come up?

[logstash-2016.04.22][[logstash-2016.04.22][3]] IllegalIndexShardStateException[CurrentState[POST_RECOVERY] operation only allowed when started/recovering, origin [PRIMARY]]
at org.elasticsearch.index.shard.IndexShard.ensureWriteAllowed(IndexShard.java:

I also heard that this issue has been fixed. But I keep getting it. Can anyone help?

2

What is happening when you get this error?

3

Nothing happens, but I get this error in the logs and then the logs also say that the cluster health is changing from "red" to "yellow" and later from "yellow" to "green".

But how can I avoid getting this error in the logs?

4

I am too seeing this error, what does it mean?