On occasions due to power outages and such, I have issues with an index getting corrupt. So here's how I fix it.
First, confirm cluster is unhealthycurl -X GET "localhost:9200/_cluster/health"
Second, find out what index is the issuecurl -X GET localhost:9200/_cluster/allocation/explain?pretty
Third, delete that indexcurl -X DELETE 'localhost:9200/graylog_29/'
Finally, create a blank index to fix issues in the GUI about it not being therecurl -X PUT "localhost:9200/graylog_29" -H 'Content-Type: application/json' -d'{ "settings" : { "index" : { } }}'