Dashboard: JavaScript error after piwik update

After updating piwik (I had to reinstall it completly) the widget-contents don’t load and no drag- / drop is possible.
And I get the following JavaScript error which also seems to be the reason for this problem:
widgetParameters is undefined
Source: <>/stats/piwik/tmp/assets/6af420abb70510fee98e0926d5e90f78.js
Line: 1020

How can I solve that problem? I have also tried to use piwik with Internet Explorer 7 - but same error here.

Thank you for your answers in advance!
With best regards
Inno

Discussion in new thread: forum.piwik.org/index.php?showtopic=12341

With best regards
Inno