Long running uncancellable transport task

[hunsw (Attila)]

I have a transport task that cannot be cancelled, but has been running for 60+ days. I have 2 questions:

1. Is there anything I can do to make this task disappear OTHER than restarting the node? (E.g. should I try to close then re-open the indices the task is trying to index into?)

2. How could this happen? (Bonus question is how to prevent/avoid this from happening again.)

Version 7.5.

{
  "completed" : false,
  "task" : {
    "node" : "xxxxxxxxxx",
    "id" : 2906259661,
    "type" : "transport",
    "action" : "indices:data/write/bulk",
    "description" : "requests[200], indices[oldindex-from-september1, oldindex-from-september-2, another-old-index-from-the-same-day-as-the-other-two]",
    "start_time_in_millis" : xxxxxxxxxx,
    "running_time_in_nanos" : xxxxxxxxxxxxxxxx,
    "cancellable" : false,
    "headers" : { }
  }
}