In Jenkins 1.508, when attempting to rename a project, clicking 'Apply' at the bottom of the 'Configure Project' page results in an empty "Error" pop-over box on the page. No error message is displayed.
However, when I press 'Save' instead of Apply, it takes me to a separate confirmation page asking "Am I sure I want to rename the project? Yes/No". So I am guessing that this confirmation step prevents 'Apply' from working. I would expect to see a pop-over window asking me to confirm the change on the same page when I click 'Apply', instead of presenting an empty error pop-over, which can be confusing.