...
Otherwise, it may be that problem happens due to dashboard left unattended, when session expires. You may try to remove all add-on gadgets from all dashboards, if it's acceptable. See https://bitbucket.org/azhdanovtempo-io/jiratimesheetservertimesheet/wiki/Usage_Tracking for how to find them.
Stopping JIRA service, rebooting the DB server, then starting JIRA service might help.
...