Open flakiness dashboard and click on small gray square that indicates test failure.

For example the following test:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=DemoSetupTest.ShowConfirmationDialogAndCancel

On the small popup dialog that shows up, click 'Failure log' link. 

What is the expected result?
Being redirected to failure logs

What happens instead?
503 Service Temporarily Unavailable