The problem occured after I installed a few plugins on my production system. So I tried to isolate the problem: I deactivated all plugins and activated each plugin after another. After I activated the analysis-collector-plugin the problem started to reoccur.
Then I set up a second, isolated instance of a jenkins server with just the default plugins. Next I installed the analysis-collector-plugin and again, the problem occured. After I installed the dashboard-view-plugin and the problem vanished.
The problem seems to happen when jenkins tries to load one or more classes of the dashboard-view-plugin. Maybe due to default configurations?