Problem

• NullPointerException thrown in the Issue Screen when creating sub-tasks e.g. 
  

• A stacktrace similar to the following may also be thrown in the UI when trying to delete an issue

  java.lang.NullPointerException
  java.lang.NullPointerException
  	at com.atlassian.jira.issue.IssueFactory$1.transform(IssueFactory.java:79)
  	at org.apache.commons.collections.CollectionUtils.collect(CollectionUtils.java:632)
  	at org.apache.commons.collections.CollectionUtils.collect(CollectionUtils.java:610)
  	at org.apache.commons.collections.CollectionUtils.collect(CollectionUtils.java:575)
  	at com.atlassian.jira.issue.index.DefaultIndexManager.reIndexIssueObjects(DefaultIndexManager.java:362)
  	at com.atlassian.jira.issue.index.DefaultIndexManager.reIndex(DefaultIndexManager.java:382)
  	at com.atlassian.jira.issue.index.DefaultIndexManager.reIndex(DefaultIndexManager.java:375)
  	at sun.reflect.GeneratedMethodAccessor1258.invoke(Unknown Source)
  	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
  	at java.lang.reflect.Method.invoke(Unknown Source)
  	at com.atlassian.util.profiling.object.ObjectProfiler.profiledInvoke(ObjectProfiler.java:83)
  	at com.atlassian.jira.config.component.SwitchingInvocationHandler.invoke(SwitchingInvocationHandler.java:28)
  	at com.sun.proxy.$Proxy131.reIndex(Unknown Source)
  	at com.atlassian.jira.issue.link.DefaultIssueLinkManager.reindexLinkedIssues(DefaultIssueLinkManager.java:149)
  	at com.atlassian.jira.issue.link.DefaultIssueLinkManager.removeIssueLinkInternal(DefaultIssueLinkManager.java:240)

• The following appears in the atlassian-jira.log
  
  

2015-08-15 21:37:52,193 http-bio-9002-exec-21 WARN xxx 1297x29965x1 yyy 10.28.0.12,127.0.0.1 /browse/BGBD-65 [jira.issue.link.LinkCollectionImpl] Issue [id=29010] links to a non-existing issue!
...
2015-08-15 21:38:12,302 http-bio-9002-exec-42 ERROR xxx 1298x30005x1 yyy 10.28.0.12,127.0.0.1 /secure/QuickCreateIssue.jspa [jira.quickedit.action.QuickCreateIssue] java.lang.NullPointerException
java.lang.NullPointerException
	at com.atlassian.jira.issue.link.DefaultIssueLinkManager.getIssueLink(DefaultIssueLinkManager.java:493)
	at com.atlassian.jira.issue.link.DefaultIssueLinkManager.createIssueLink(DefaultIssueLinkManager.java:101)

Cause

This is a data integrity issue. There may be some issue links pointing to non-existent JIRA issue IDs in the database

Resolution

This can be fixed by JIRA's Database Integrity Checker

• Run the integrity checker: navigate through Administration Menu > System > Troubleshooting & Support > Integrity Checker
• Ensure that all options under 'Check Issue Relations' are selected, and then click the 'check' button.
• click to Fix all errors found