Sometimes after app update it gets disabled. When you try to re-enable it, you get an error that highly likely won’t provide you much info about the real reason why app is not starting. Another possible case here is major upgrades (to JIRA 7.4, or to JIRA 8.0 for example) that leads to the same situation with 3rd party apps.
In most cases the problem is caused by apps cache you need to get rid of. Here are the steps to do it:
Shut down JIRA
Delete the following hidden apps cache directories:
JIRA_HOME/plugins/.bundled-plugins
JIRA_HOME/plugins/.osgi-plugins
Restart JIRA
Deleted directories will be recreated on JIRA reboot with new apps cache.
Alternatively you can achieve same results with these console commands afer you shut down your instance:
sudo rm -r /var/atlassian/application-data/jira/plugins/.bundled-plugins
sudo rm -r /var/atlassian/application-data/jira/plugins/.osgi-plugins