DC app failing to start
In case you have problem enabling Advanced Portal Reports due to "java.lang.IllegalStateException: The bundle is uninstalled" exception, please follow the steps in this article to fix this:
The restart usually purges the plugins cache but you can also run it manually.
Stop JIRA instance
Delete JIRA_HOME/plugins/.bundled-plugins and JIRA_HOME/plugins/.osgi-plugins ((warning) just these two folders!)
Restart Jira