# Cluster state often in yellow: data node and master are running but failed to ping each other **URL:** \ **Category:** Elasticsearch\ **Created:** [April 10, 2018, 8:02am UTC](https://discuss.elastic.co/t/cluster-state-often-in-yellow-data-node-and-master-are-running-but-failed-to-ping-each-other/127440 "2018-04-10T08:02:19Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![MarkDai](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@MarkDai](https://discuss.elastic.co/u/MarkDai)\ **Post date:** [April 13, 2018, 6:03am UTC](https://discuss.elastic.co/t/cluster-state-often-in-yellow-data-node-and-master-are-running-but-failed-to-ping-each-other/127440/3 "2018-04-13T06:03:05Z")
Found the reason, it's a bug of ES 5.1.1. Hope anyone else can get there easily. > [@ES 5.1.1: Cluster loses a node randomly every few hours. Error: Message not fully read (response) for requestId](https://discuss.elastic.co/t/es-5-1-1-cluster-loses-a-node-randomly-every-few-hours-error-message-not-fully-read-response-for-requestid/71208): > > Hi all, I'm wondering if anybody else has seen this, or can help me understand what exactly is going on. We have a 5 data nodes/3 masters/1client node cluster at version 5.1.1. The data nodes are usually fairly busy, indexing around 5000 documents/s for primary shards. They seem to be keeping up with load though. Although every few hours (not always the same number of hours/times in the day) the cluster loses one of the nodes(not always the same) and as expected the replicas are promoted to… --- _[View the full topic](https://discuss.elastic.co/t/cluster-state-often-in-yellow-data-node-and-master-are-running-but-failed-to-ping-each-other/127440)._