After a Jenkins application and all plugins-update, new and existing multi-configuration projects have lost the ability to add an Agents axis.  Running through Chrome's debugger, this error displays when the Agents button is selected under the "Add axis" option.  

Uncaught SyntaxError: Invalid or unexpected token 
  at eval (<anonymous>) 
  at geval (hudson-behavior.js:471:30)
  [...]

This is occurring on two production servers, both of which have many nodes defined.  It is not occurring on two development servers, which only have three to six nodes defined.  . I added all the nodes from one production server to one dev server, but that did not have an impact.  

In the /configure screen, when I select "Add axis" and then "Agents", no window and no errors are displayed in the GUI.  (In the dev environment, when I do that I get the Agents/Name/Node\Label window.)  I also note in dev I see a checkName "step", but that does not occur in prod.

Using Chrome to see what I could figure out, I captured some errors.  Attached.

Please let me know what additional information I can provide.  This is impacting existing multi-configuration projects, which no longer have the agents available to them.