Failed to Modify the Elasticsearch Cluster Specifications

Symptom

I failed to modify the cluster specifications and an error message is displayed on the console.

Figure 1 CSS.0073 error

Figure 2 CSS.0011 error

Possible Causes

The number of replicas is not set for the current cluster. The background rejects the request for changing the specifications. You need to set the number of replicas before modifying the specifications. Otherwise, shards may be lost.

Solution

PUT /index/_settings
{
    "number_of_replicas" : 1 //Number of replicas
}