Similar to JENKINS-11074 and as stated in JENKINS-6542 I am opening a new issue as it looks different to the ones before:

It worked without this error for some time, but suddenly it started and does not go away even after restarting Jenkins. I don't think I installed any additional plugin in the meantime as the Jenkins-setup was stable for some time now.

I get the following Javascript errors:

syntax error
setTimeout(function(){a.removeClass(v,...{o=true;}j=this._getFormAttributes(r);
container-min.js (Zeile 17)

extend failed, please check that all dependencies are included.
if(typeof YAHOO=="undefined"||!YAHOO){...(/^\s+|\s+$/g,"");}catch(k){return j;
yahoo-min.js (Zeile 7)

YAHOO.widget.Tooltip is not a constructor
tooltip = new YAHOO.widget.Tooltip("tt", {context:[], zindex:999});
hudson...vior.js (Zeile 505)

Jenkins is ver. 1.444

Installed plugins and source of config-page are attached