Hi, I'm currently implementing the last things to finish OpenID authentication support but I have some problems with the query manager. I'm trying to get the document (should be only one) which an attached OpenIdIdentifier object whose "identifier" string property's value has some specific value. I didn't found any documentation apart http://markmail.org/message/jt6m2huqr4r6hvk6 and http://dev.xwiki.org/xwiki/bin/view/Design/XWiki+Query+Language+Specificatio.... I tried to achieve this by the following code: public static String findOpenIDUser(String openid_identifier, XWikiContext context) throws XWikiException { XWiki xwiki = context.getWiki(); QueryManager qm = xwiki.getStore().getQueryManager(); Query search_user; if (qm.hasLanguage(Query.HQL)) { search_user = qm.createQuery(", BaseObject as obj, StringProperty as prop where doc.fullName = obj.name and obj.className = 'XWiki.OpenIdIdentifier' and obj.id=prop.id.id and prop.id.name='identifier' and prop.value = ':identifier'", Query.HQL); } else if (qm.hasLanguage(Query.XPATH)) { search_user = qm.createQuery("/*/*[obj/XWiki/OpenIdIdentifier/@xp:identifier = ':identifier'] ", Query.XPATH); } else throw new RuntimeException(); search_user.bindValue("identifier", openid_identifier); List<XWikiDocument> found_users = search_user.setLimit(1).execute(); if (found_users.size() > 0) { if (log.isDebugEnabled()) { log.debug("OpenID " + openid_identifier + " already registered."); } return found_users.get(0).getFullName(); } return null; } but all I get is a NullPointerException when qm.createQuery(..., Query.HQL) is called. What's wrong with my code? java.lang.NullPointerException at com.xpn.xwiki.store.query.AbstractQueryManager.createQuery(AbstractQueryManager.java:73) at com.xpn.xwiki.user.impl.openid.OpenIDHelper.findOpenIDUser(OpenIDHelper.java:109) at com.xpn.xwiki.user.impl.xwiki.MyFormAuthenticator.processLogin(MyFormAuthenticator.java:201) at com.xpn.xwiki.user.impl.xwiki.MyFormAuthenticator.processLogin(MyFormAuthenticator.java:178) at com.xpn.xwiki.user.impl.xwiki.XWikiAuthServiceImpl.checkAuth(XWikiAuthServiceImpl.java:205) at com.xpn.xwiki.XWiki.checkAuth(XWiki.java:3518) at com.xpn.xwiki.user.impl.xwiki.XWikiRightServiceImpl.checkAccess(XWikiRightServiceImpl.java:139) at com.xpn.xwiki.XWiki.checkAccess(XWiki.java:3526) at com.xpn.xwiki.XWiki.prepareDocuments(XWiki.java:4432) at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:190) at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:115) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432) at javax.servlet.http.HttpServlet.service(HttpServlet.java:710) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.xpn.xwiki.web.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:287) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:112) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:619)