After Create My ES cluster included only 3 nodes each of nodes is "master and data node" , when trying to check cluster health using "9200/_cluster/health?pretty'" getting an error

[m_5amy (mahmoud samy)]

This is the error returned after check cluster health

{
  "error" : {
    "root_cause" : [
      {
        "type" : "master_not_discovered_exception",
        "reason" : null
      }
    ],
    "type" : "master_not_discovered_exception",
    "reason" : null
  },
  "status" : 503
}