No such indices in ElasticSearch

We are currently running an Elasticsearch & Kibana (8.14.3) cluster with:

  • 3 master nodes and 6 data nodes

  • Also, we are using Metricbeat ver 8.14.3 for monitoring the cluster ( we are enabled xpack.monitoring feature )

This morning, I received a warning “failed to delete indices” from the current master..
I checked the log file (29-08) and found:

[2025-08-29T10:00:00,00][INFO] [o.e.x.m.e.l.LocalExporter] [elastic-current-master] cleaning up [2] old indices

[2025-08-29T10:00:00,00][INFO] [o.e.x.m.e.l.LocalExporter] [elastic-current-master] cleaning up [2] old indices

[2025-08-29T10:00:00,00][INFO] [o.e.x.m.MetadataDeleteIndexService] [elastic-current-master] [.monitoring-es-7-2025-08-22]/Cj&U39slfcmlla] deleting index

[2025-08-29T10:00:00,00][INFO] [o.e.x.m.MetadataDeleteIndexService] [elastic-current-master] [.monitoring-kibana-7-2025-08-22]/bWgDTYdfdskmgap] deleting index

[2025-08-29T10:00:00,055][INFO] [o.e.x.m.l.LocalExporter] [elastic-current-master] [.monitoring-kibana-7-2025-08-22]/bWgDTYdfdskmgap] deleting index

[2025-08-29T10:00:00,055][INFO] [o.e.x.m.l.LocalExporter] [elastic-current-master] [.monitoring-es-7-2025-08-22]/bWgDTYdfdskmgap] deleting index
org.elasticsearch.index.IndexNotFoundException: no such index [.monitoring-kibana-7-2025-08-22]

[2025-08-29T10:30:00,055][INFO] [o.e.x.s.SnapshotRetentionTask] [elastic-current-master] starting SLM retention snapshot cleanup task

Also, I checked other log files from 26-08 to 28-08, there’s no message like that..

The log files from 26-08 to 28-08 show the same messages, except they don’t include the message ‘no such index’

I checked ILM policy => No policy for it ( only for .monitoring-*-8..) since we are using ver 8
I checked cronjob ( use sudo as well ) => No cron job for it
I checked the index disk space => Still good

I assume that someone must have deleted it manually… I’m not sure

If anyone has better suggestions or experience handling this kind of issue, please let me know

Thanks in advance