Failed to process cluster event (index-aliases) within 30s

[Anca_Muresan]

Hello everyone ,

I get this error very frequently

Elasticsearch\Common\Exceptions\ServerErrorResponseException: {"error":{"root_cause":[{"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (index-aliases) within 30s"}],"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (index-aliases) within 30s"},"status":503} in /var/www/html/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Connections/Connection.php:682

I use elastic 6.7.2 and have the following cluster details :

{
  "cluster_name" : "system-reports-data",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 9,
  "number_of_data_nodes" : 6,
  "active_primary_shards" : 161,
  "active_shards" : 322,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 0,
  "delayed_unassigned_shards" : 0,
  "number_of_pending_tasks" : 116,
  "number_of_in_flight_fetch" : 0,
  "task_max_waiting_in_queue_millis" : 739564,
  "active_shards_percent_as_number" : 100.0
}

From what I've read, the master cannot update cluster state within 30s interval. Please correct me if i am wrong.
Does anybody have an idea how to fix this problem or at least telling me if something does not look good with my cluster? Is increasing master timeout a good solution?