There is an error below.
2021-04-09 16:44:17,719+0900 NodeReindexServiceThread:thread-0 INFO [c.a.j.index.ha.DefaultNodeReindexService] [INDEX-REPLAY] Node re-index service is not running: currentNode.isClustered=true, notRunningCounter=216, paused=true, lastPausedStacktrace=java.lang.Throwable
at com.atlassian.jira.index.ha.DefaultNodeReindexService.pause(DefaultNodeReindexService.java:215)
at com.atlassian.jira.util.index.CompositeIndexLifecycleManager.reIndexAll(CompositeIndexLifecycleManager.java:62)
at com.atlassian.jira.util.index.CompositeIndexLifecycleManager.reIndexAll(CompositeIndexLifecycleManager.java:51)
at com.atlassian.jira.web.action.admin.index.ReIndexAsyncIndexerCommand.doReindex(ReIndexAsyncIndexerCommand.java:27)
at com.atlassian.jira.web.action.admin.index.AbstractAsyncIndexerCommand.call(AbstractAsyncIndexerCommand.java:63)
at com.atlassian.jira.web.action.admin.index.ReIndexAsyncIndexerCommand.call(ReIndexAsyncIndexerCommand.java:18)
at com.atlassian.jira.web.action.admin.index.AbstractAsyncIndexerCommand.call(AbstractAsyncIndexerCommand.java:26)
at com.atlassian.jira.task.TaskManagerImpl$TaskCallableDecorator.call(TaskManagerImpl.java:533)
at com.atlassian.jira.task.TaskManagerImpl$TaskCallableDecorator.call(TaskManagerImpl.java:491)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at com.atlassian.jira.task.ForkedThreadExecutor$ForkedRunnableDecorator.run(ForkedThreadExecutor.java:216)
at java.lang.Thread.run(Thread.java:823)
Why does it happen?