Data model for Postgresql not updated on migration to 3.1 ?

Trying to upgrade my 2 xwiki instances to 3.1.
Afterwards the rendering of the pages was broken (mainly the top menu bar).
Rolling back to 3.0 and the pages appears normal.

One Problem was left in the WYSIWYG Editor - the menu bar was missing.
Going to the XWiki.WysiwygEditorConfig Page I tried to add the data from the 3.1 release notes. (Yes this was silly - and now I have entered the correct data)

This triggers an exception:

Caused by: org.postgresql.util.PSQLException: ERROR: value too long for type character varying(255)