Symptoms

The following error messages are reported in the JIRA log file:

java.lang.NullPointerException
at com.atlassian.jira.upgrade.tasks.UpgradeTask_Build602.migrateGroups(UpgradeTask_Build602.java:535)
at com.atlassian.jira.upgrade.tasks.UpgradeTask_Build602.doUpgrade(UpgradeTask_Build602.java:93)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.doUpgradeTaskSucess(UpgradeManagerImpl.java:578)
at com.atlassian.jira.upgrade.UpgradeManagerImpl.runUpgradeTasks(UpgradeManagerImpl.java:482)
...

Cause

There is a user group missing "name" field in JIRA, which breaks group migration to JIRA 4.3+ version.

Workaround

1. Back up JIRA your original JIRA instance (the one before the upgade)
2. Shutdown JIRA

3. Run the below SQL query against your original JIRA's database:

   update groupbase set groupname='DATA-FIX' where groupname is null
   

4. Reboot JIRA instance
5. Locate 'DATA-FIX' group in JIRA, delete or rename it.
6. Generate a new backup XML file
7. Redo the upgrade with the new backup file.

Resolution

Track the resolution at JRA-24172.