upgrade xwiki to 1.0b2 encounter "Could not initialize main XWiki context"

Hi, we were using xwiki 0.9.840, and recently I test to update with 1.0b2 with old database. as we are using postgresql as our db backend, I need to update xwiki with database migration (which I have seen 1.0b2 supports migration), I have modified the hibernate.cfg.xml to postgresql configuration. our system is: * gentoo 2006.1 * tomcat: 5.0.27-r6 * postgresql: postgresql-8.0.8 * jdbc: postgresql-8.0-315.jdbc3.jar after start tomcat, I connect to xwiki page and get following exception: exception javax.servlet.ServletException: Error number 3 in 0: Could not initialize main XWiki context Wrapped Exception: Error number 3201 in 3: Exception while saving document XWiki.TagClass Wrapped Exception: Could not execute JDBC batch update org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:535) org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:433) org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236) org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196) org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) javax.servlet.http.HttpServlet.service(HttpServlet.java:689) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:121) root cause com.xpn.xwiki.XWikiException: Error number 3 in 0: Could not initialize main XWiki context Wrapped Exception: Error number 3201 in 3: Exception while saving document XWiki.TagClass Wrapped Exception: Could not execute JDBC batch update com.xpn.xwiki.XWiki.getMainXWiki(XWiki.java:223) com.xpn.xwiki.XWiki.getXWiki(XWiki.java:303) com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:96) org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431) org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236) org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196) org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) javax.servlet.http.HttpServlet.service(HttpServlet.java:689) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:121) i believe that there are people using postgresql, is that you have experienced same error? or it's not the problem with postgresql? any help to solve this problem? best regards, muzi