Jira: Activity Stream stopped working, throws error

Using Atlassian Jira, and having faulty activity streams? Also, using Oracle?
You have an issue (usually from an email), where the subject is empty.
In Oracle, the empty string is stored as null.
Therefore, when Jira reads back an issue, its subject will be null (not empty string).
This screws up the Activity Stream gadget, as it calls String.substring() on it, without any error checking.

Get rid of the null subjects.

UPDATE JIRAISSUE SET SUMMARY = '(no subject)' WHERE SUMMARY IS NULL;