My manager double clicked on start progress when he was evaluating the software. This caused a:
HTTP Status 404 - No view for result [error] exists for action [WorkflowUIDispatcher]
type Status report

message No view for result [error] exists for action [WorkflowUIDispatcher]

description The requested resource (No view for result [error] exists for action [WorkflowUIDispatcher]) is not available.
Apache Tomcat/4.1.29

When he went back to the screen he kept getting this message when he single clicked on start progress. By manually refreshing the screen (F5) it updated to show that the project was now stopped.

This is fully reproducible on my PC too.