[xwiki-users] Could not synchronize database state with session

Hi Everyone, I was just trying to upgrade from 3.0.1 to 4.4. as I figured I can't save XWikiPreferences anymore: 13:07:17,307 [http://0x64plusxwiki.local.0x64plus.de:8080/xwiki/bin/saveandcontinue/XWiki…] [http://0x64plusxwiki.local.0x64plus.de:8080/xwiki/bin/save/XWiki/XWikiPrefe…] ERROR .AbstractFlushingEventListener - Could not synchronize database state with session org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [com.xpn.xwiki.objects.IntegerProperty#<?xml version="1.0" encoding="UTF-8"?> <showcomments></showcomments> ] at org.hibernate.persister.entity.AbstractEntityPersister.check(AbstractEntityPersister.java:1769) … Is there any way to fix this? Or force the save of my current XWikiPreferences? Thanks in advance, Florian