Problem

Trying to delete a Jira issue results in an error.

Diagnosis

• The delete issue dialog may hint that some subtasks will be deleted when deleting that issue, but you may perhaps be unable to find some of the subtasks hinted on the delete issue screen.

• If you find an error similar to the one below in the atlassian-jira.log file, then this KB article is relevant:

  2016-02-23 17:23:15,018 http-nio-80-exec-5 ERROR      [o.a.c.c.C.[.[localhost].[/].[action]] Servlet.service() for servlet [action] in context with path [] threw exception [java.lang.NullPointerException] with root cause
  java.lang.NullPointerException
  	at com.atlassian.jira.issue.managers.DefaultIssueDeleteHelper.removeSubTasks(DefaultIssueDeleteHelper.java:245)
  	at com.atlassian.jira.issue.managers.DefaultIssueDeleteHelper.deleteIssue(DefaultIssueDeleteHelper.java:129)
  	at com.atlassian.jira.issue.managers.DefaultIssueManager.deleteIssue(DefaultIssueManager.java:897)
  	at com.atlassian.jira.bc.issue.DefaultIssueService.delete(DefaultIssueService.java:392)
  	at com.atlassian.jira.bc.issue.DefaultIssueService.delete(DefaultIssueService.java:362)
  	at com.atlassian.jira.web.action.issue.DeleteIssue.doExecute(DeleteIssue.java:27)

Cause

This is a database-integrity issue. Jira may be making reference to sub-tasks that no longer exist.

Workaround

1. Run the Database Integrity Checker and fix all errors.
2. Run a Jira Re-indexing after step #1