What version are you on? - 5.1.2
What OS? - RHEL 6.8
How did you install Elasticsearch? - unzip the zip file
What does your config look like?
What does the entire log entry look like? Post the whole thing, not part of it
same error repeated
[2017-11-20T00:02:54,840][INFO ][o.e.e.NodeEnvironment ] [-na-uat] heap size [1.9gb], compressed ordinary object pointers [true]
[2017-11-20T00:02:54,841][INFO ][o.e.n.Node ] [-na-uat] node name [-na-uat], node ID [N50Yb36rR8-2aLxHCepXBQ]
[2017-11-20T00:02:54,844][INFO ][o.e.n.Node ] [-na-uat] version[5.1.2], pid[7767], build[c8c4c16/2017-01-11T20:18:39.146Z], OS[Linux/2.6.32-696.6.3.el6.x86_64/amd64], JVM[Oracle Corporation/Java HotSpot(TM) 64-Bit Server VM/1.8.0_74/25.74-b02]
[2017-11-20T00:02:55,813][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [aggs-matrix-stats]
[2017-11-20T00:02:55,813][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [ingest-common]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [lang-expression]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [lang-groovy]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [lang-mustache]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [lang-painless]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [percolator]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [reindex]
[2017-11-20T00:02:55,814][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [transport-netty3]
[2017-11-20T00:02:55,815][INFO ][o.e.p.PluginsService ] [-na-uat] loaded module [transport-netty4]
[2017-11-20T00:02:55,815][INFO ][o.e.p.PluginsService ] [-na-uat] no plugins loaded
[2017-11-20T00:02:58,445][INFO ][o.e.n.Node ] [-na-uat] initialized
[2017-11-20T00:02:58,445][INFO ][o.e.n.Node ] [-na-uat] starting ...
[2017-11-20T00:02:58,620][INFO ][o.e.t.TransportService ] [-na-uat] publish_address {...:8903}, bound_addresses {0.0.0.0:8903}
[2017-11-20T00:02:58,627][INFO ][o.e.b.BootstrapCheck ] [-na-uat] bound or publishing to a non-loopback or non-link-local address, enforcing bootstrap checks
[2017-11-20T00:03:28,649][WARN ][o.e.n.Node ] [-na-uat] timed out while waiting for initial discovery state - timeout: 30s
[2017-11-20T00:03:28,666][INFO ][o.e.h.HttpServer ] [-na-uat] publish_address {...:8900}, bound_addresses {0.0.0.0:8900}
[2017-11-20T00:03:28,667][INFO ][o.e.n.Node ] [-na-uat] started
[2017-11-20T00:03:28,967][DEBUG][o.e.a.a.i.c.TransportCreateIndexAction] [-na-uat] no known master node, scheduling a retry
[2017-11-20T00:03:29,133][DEBUG][o.e.a.a.i.c.TransportCreateIndexAction] [-na-uat] no known master node, scheduling a retry
[2017-11-20T00:03:29,144][DEBUG][o.e.a.a.i.c.TransportCreateIndexAction] [-na-uat] no known master node, scheduling a retry
[2017-11-20T00:04:28,971][DEBUG][o.e.a.a.i.c.TransportCreateIndexAction] [-na-uat] timed out while retrying [indices:admin/create] after failure (timeout [1m])
[2017-11-20T00:04:28,974][WARN ][r.suppressed ] path: /xxxx/xxxxx/xxxxx, params: {index=xxxxx-11062017, id=Bond-xxxx, type=xxxx}
org.elasticsearch.discovery.MasterNotDiscoveredException: null
at org.elasticsearch.action.support.master.TransportMasterNodeAction$AsyncSingleAction$5.onTimeout(TransportMasterNodeAction.java:214) [elasticsearch-5.1.2.jar:5.1.2]
at org.elasticsearch.cluster.ClusterStateObserver$ContextPreservingListener.onTimeout(ClusterStateObserver.java:350) [elasticsearch-5.1.2.jar:5.1.2]
at org.elasticsearch.cluster.ClusterStateObserver$ObserverClusterStateListener.onTimeout(ClusterStateObserver.java:240) [elasticsearch-5.1.2.jar:5.1.2]
at org.elasticsearch.cluster.service.ClusterService$NotifyTimeout.run(ClusterService.java:964) [elasticsearch-5.1.2.jar:5.1.2]
at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:458) [elasticsearch-5.1.2.jar:5.1.2]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_74]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_74]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_74]