ElasticSearch Replicas

If cluster is stuck in "Yellow" state, one of the reason might be unassigned pieces of data

You can check it by calling: GET _cluster/health

unassigned_shards not equal to 0 means that there are pieces of data in cluster which can not be assigned anywhere by some reason

We can try to do following:

PUT vacancylist6/_settings
{
  "number_of_replicas": 1
}

Reset replicas to zero and then back to one

Then call _cluster/health look for unasigned_shards - number should go away into relocating_shards and then switch to zero