Find Issue, Issue Attributes -> Assignee Specify User, Click on icon (opens user browser), search for a user with specific email address, hit enter (to start the search) turns into:

2006-08-16 09:54:40,085 INFO [com.atlassian.jira.web.filters.AccessLogFilter] admin http://10.60.1.1:8080/jira/secure/popups/UserPickerBrowser.jspa 472716-1205 23
2006-08-16 09:54:45,302 INFO [com.atlassian.jira.web.action.admin.user.UserPickerBrowser] Setting start to [Ljava.lang.String;@17db797 failed. [java.lang.NumberFormatException For input string: "[Ljava.lang.String;@17db797"

The wanted user does show up and can be selected. The functionality does not seem to be affected by this issue. It is merely an open question what to do with this log entry. Anything I can change, or should I ignore this?

Any help would be greatly appreciated.