Dears, I have tryed to upgrade my XWiki from 2.1.1 to 2.6, but I have an exception: ---------------------------------- type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception javax.servlet.ServletException: Servlet execution threw an exception com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:129) com.xpn.xwiki.wysiwyg.server.filter.ConversionFilter.doFilter(ConversionFilter.java:152) com.xpn.xwiki.plugin.webdav.XWikiDavFilter.doFilter(XWikiDavFilter.java:68) org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:218) org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:112) root cause java.lang.NoClassDefFoundError: org/xwiki/rendering/listener/Attachment java.lang.Class.forName0(Native Method) java.lang.Class.forName(Unknown Source) ................. -------------- And really there isn't Attachment.class in xwiki-core-rendering-api-2.6.jar! (there is in 2.1.1) What can I do? Best regards Boris Gorelik