tested using multiple browsers on Windows and Linux
Selecting an item, then selecting an operation (for example, "Promote to home page" or "Demote from home page"), then clicking "Execute" produces error messages similar to those in the attached image. Sometimes an error message happens immediately after "Execute" is clicked; but usually the error occurs after "Confirm" is clicked on the screen that follows the "Execute" click.
A workaround is available, using the Edit screens for each individual item. However, the promoting and demoting using the HomePage Manage page saves time.
This problem was first noticed around May 24.