Symptoms:

Tempo is missing from the top bar, and accessing any tempo page directly results in a 404 error.

Cause:

It is suspected that an upgrade today caused Tempo to not come up properly.

Workaround:

1. Click the cog in the top right of JIRA and select 'Add-ons'
2. Click 'Manage Add-ons' on the left
3. Search for 'Tempo'
4. Disable Tempo Timesheets
5. Click Don't Send Feedback when prompted
6. Enable Tempo Timesheets