Some editors of inspector cannot be loaded after a fresh installation

I installed Neos 2.3.8 and created a new site as described here: [SOLVED] Setting up a new site leads to a 500 internal server error
Few seconds after I logged into the backend four errors are displayed:

Error loading inspector
Inspector editor for property "twitterCardImage" could not be loaded. See console for further details.
Error loading inspector
Inspector editor for property "openGraphImage" could not be loaded. See console for further details.
Error loading inspector
Inspector editor for property "_hiddenAfterDateTime" could not be loaded. See console for further details.
Error loading inspector
Inspector editor for property "_hiddenBeforeDateTime" could not be loaded. See console for further details.

Further I am not able to edit the first page (homepage). It is possible to add some elements to the Content Collection, but these elements were not be displayed anywhere.
I have looked at the configuration of Neos 3.2 but couldn’t found what the root cause of this problem is. How can I solve this problem? Thanks for your investigations.

There’s should more information in the JavaScript debugging console. However make sure you clear all browser cache before anything else. It’s usually due to a slow connection or some caching issue.