After updating civicrm from version 4.7.10 to 4.7.11, the configure fucton does not work any more.
There are no buttons any more in the configuration dahsboard:
and drag and drop does not work anymore.
Meanwhile the Dashboard itself stays robust and in good health and keeps working okay.
I tried flushing all caches in the site, and sometimes this helps, and the dashboard then looks correct again and functions, but minutes later the image changes back to the button-less like the one in the image above. I checked with Firebug and this reports a javascript error, with a very long text that I do not understand at all. It is a pity because this has worked all the time in the versions before 4.7.11.
Any advice on what to do?