Actually, I think this issue goes deeper - changing my job name through the job configuration screen broke my build. Changing it back refixed the build. It seemed perhaps that the ..../workspace/buildname directory perhaps didn't change over with the name change, so the build was left pointing at the wrong place. I don't have ssh access to the server I am using Jenkins on to confirm...

I'm seeing this with 1.466. Steps I used to reproduce:

I have one build named "xyz"
I create a new build called "xyz-temp"
I delete "xyz" using the Jenkins interface
I try to rename "xyz-temp" to "xyz" hit Apply and I get an empty pop up error box, hit "Save" and I get a Failed to Parse Form data error. And the form JSON has an empty key:

JSON={"":"xyz (Trunk Branch)\n<br/>.............

Seeing this in 1.480.2

Just upgraded to 1.543 and seeing it there as well.

JENKINS-17401 notes that Apply does not work for job renames; you must use Save. Not clear if there is more to this bug report than that.

Closing this after a month without responses to Jesse's comment.

Anyone: Feel free to reopen if this isn't a duplicate of JENKINS-17401, but please edit this issue to include an explanation how this is different.