I also got this issue after upgrade to Jenkins ver. 1.530: At job configuration page, the [LOADING] frame is shown after load is complete.
Then config fails to save changes with error:
Status Code: 400
Exception: This page expects a form submission
Jenkins ver. 1.530.
All plugins are up-to-date.
Google Chrome Version 27.0.1453.116 m
Mozilla Firefox 23.0.1
Internet Explorer 9.0