Hello, it is the plugin "EventList" which causes the issue.
It is possible to change something in my configuration or can I change anything on the accordion menu files?
Best regards, Stefan
Hello, first verify that it is the plugin that is causing the issue by disabling it and make sure the page loads correctly after that. If it does then there is an issue with this plugin and won't be compatible with the accordion menu or any module that uses the default mootools.js file.