It looks like your Elasticsearch cluster's action.auto_create_index
setting is
preventing Kibana from automatically creating an index to store saved objects. Kibana uses this
Elasticsearch feature because it is the best way to make sure that the saved object index uses
the correct mappings/schema, and it allows Kibana to poll Elasticsearch less often.
Unfortunately, until this issue is fixed you won't be able to save anything in Kibana.
action.auto_create_index: false
from your Elasticsearch configuration file