I had to increase the log level in configuration log page to view the details.
Now I got a disgusting "nullpointerexception" thrown by the odf.objectView:
ERROR 2016-04-26 16:50:28,072 [http-nio-14001-exec-2] niku.xql2 (clarity:admin:14257115__74563E81-9870-4459-835B-4D18ADE98353:odf.objectViews) Internal Processing exception
java.lang.NullPointerException
at com.niku.odf.griphendor.grid.Column.marshal(Column.java:1404)
at com.niku.odf.griphendor.grid.GridMetadata.marshal(GridMetadata.java:2351)
at com.niku.odf.griphendor.grid.GridAdminHandler.getGrid(GridAdminHandler.java:450)
at com.niku.odf.griphendor.grid.GridAdminHandler.postProcess(GridAdminHandler.java:308)
at com.niku.xql2.XQLVisitor.postProcess(XQLVisitor.java:1419)
at com.niku.union.xml.dom.DOMWalker.postProcess(DOMWalker.java:210)
at com.niku.union.xml.dom.DOMWalker.traverseIntern(DOMWalker.java:94)
at com.niku.union.xml.dom.DOMWalker.traverse(DOMWalker.java:51)
at com.niku.xql2.handlers.MatchHandler.preProcess(MatchHandler.java:129)
at com.niku.xql2.XQLVisitor.preProcess(XQLVisitor.java:1385)
at com.niku.union.xml.dom.DOMWalker.preProcess(DOMWalker.java:194)
at com.niku.union.xml.dom.DOMWalker.traverseIntern(DOMWalker.java:74)
at com.niku.union.xml.dom.DOMWalker.traverse(DOMWalker.java:51)
at com.niku.xql2.handlers.LoopHandler.processObject(LoopHandler.java:384)
at com.niku.xql2.handlers.LoopHandler.processSet(LoopHandler.java:255)
at com.niku.xql2.handlers.LoopHandler.preProcess(LoopHandler.java:212)
at com.niku.xql2.XQLVisitor.preProcess(XQLVisitor.java:1385)
at com.niku.union.xml.dom.DOMWalker.preProcess(DOMWalker.java:194)
at com.niku.union.xml.dom.DOMWalker.traverseIntern(DOMWalker.java:74)
at com.niku.union.xml.dom.DOMWalker.traverseIntern(DOMWalker.java:92)
at com.niku.union.xml.dom.DOMWalker.traverseIntern(DOMWalker.java:92)
at com.niku.union.xml.dom.DOMWalker.traverseIntern(DOMWalker.java:92)
at com.niku.union.xml.dom.DOMWalker.traverse(DOMWalker.java:36)
at com.niku.xql2.XQLProcessor.process(XQLProcessor.java:257)
at com.niku.xql2.XQLProcessor.process(XQLProcessor.java:283)
at com.niku.xql2.binding.ServiceControlBindingXql.processFile(ServiceControlBindingXql.java:387)
at com.niku.xql2.binding.ServiceControlBindingXql.getDocument(ServiceControlBindingXql.java:270)
at com.niku.xql2.binding.ServiceControlBindingXql.processRequest(ServiceControlBindingXql.java:154)
at com.niku.union.service.ServiceControlImpl.processRequest(ServiceControlImpl.java:902)
at com.niku.union.service.ServiceControlImpl.processRequest(ServiceControlImpl.java:212)
at com.niku.union.web.WebServiceAdapter.processRequest(WebServiceAdapter.java:219)
at com.niku.union.web.PortletController.processServiceRequest(PortletController.java:1419)
at com.niku.union.web.PortletController.processAuthorizedPortlet(PortletController.java:902)
at com.niku.union.web.PortletController.processPageActionRequest(PortletController.java:397)
at com.niku.union.web.PortletController.processRequest(PortletController.java:164)
at com.niku.union.web.WebActionController.processAction(WebActionController.java:1433)
at com.niku.union.web.WebActionController.processRequest(WebActionController.java:176)
at com.ca.clarity.uif.service.vxml.VXMLService.processRequest(VXMLService.java:456)
at com.ca.clarity.uif.UIServlet.service(UIServlet.java:69)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.niku.union.web.filter.ClarityContentFilter.doFilter(ClarityContentFilter.java:148)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.niku.union.web.filter.XSSFilter.doFilter(XSSFilter.java:80)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.niku.union.web.filter.GZIPResponseFilter.doFilter(GZIPResponseFilter.java:138)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.niku.union.web.filter.TenantSetupFilter.doFilter(TenantSetupFilter.java:50)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.niku.union.web.filter.CharsetFilter.doFilter(CharsetFilter.java:45)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.filters.AddDefaultCharsetFilter.doFilter(AddDefaultCharsetFilter.java:88)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at com.niku.union.web.valves.ErrorPageRedirectValve.invoke(ErrorPageRedirectValve.java:65)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)