RuntimeException is thrown each time People Directory is viewed

I get this kind of exception when requesting People Directory (http://site/webapp/browsepeople.action). On the page only the account who requested the page is rendered.

[13:15:45.213] 2007-04-18 13:15:45,212 ERROR [resin-tcp-connection-*:7811-13] [confluence.search.actions.SearchBean] search Error while searching the site!
[13:15:45.213] – url: /wiki-devel/browsepeople.action | userName: tj | action: browsepeople
[13:15:45.213] java.lang.RuntimeException: no terms in field fullNameSortable - cannot determine sort type
[13:15:45.213] at org.apache.lucene.search.FieldCacheImpl.getAuto(FieldCacheImpl.java:325)
[13:15:45.213] at org.apache.lucene.search.FieldSortedHitQueue.comparatorAuto(FieldSortedHitQueue.java:341)
[13:15:45.213] at org.apache.lucene.search.FieldSortedHitQueue.getCachedComparator(FieldSortedHitQueue.java:184)
[13:15:45.213] at org.apache.lucene.search.FieldSortedHitQueue.<init>(FieldSortedHitQueue.java:58)
[13:15:45.213] at org.apache.lucene.search.TopFieldDocCollector.<init>(TopFieldDocCollector.java:44)
[13:15:45.213] at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:108)
[13:15:45.213] at org.apache.lucene.search.Hits.getMoreDocs(Hits.java:65)
[13:15:45.213] at org.apache.lucene.search.Hits.<init>(Hits.java:52)
[13:15:45.213] at org.apache.lucene.search.Searcher.search(Searcher.java:62)
[13:15:45.213] at com.atlassian.bonnie.search.LuceneSearcher$6.perform(LuceneSearcher.java:212)
[13:15:45.213] at com.atlassian.bonnie.LuceneConnection.withSearch(LuceneConnection.java:139)
[13:15:45.213] at com.atlassian.bonnie.search.LuceneSearcher.searchForFields(LuceneSearcher.java:208)
[13:15:45.213] at com.atlassian.confluence.search.actions.SearchBean.search(SearchBean.java:76)
[13:15:45.213] at com.atlassian.confluence.user.actions.PeopleDirectoryAction.search(PeopleDirectoryAction.java:110)
[13:15:45.213] at com.atlassian.confluence.user.actions.PeopleDirectoryAction.doBrowse(PeopleDirectoryAction.java:98)
[13:15:45.213] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[13:15:45.213] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[13:15:45.213] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[13:15:45.213] at java.lang.reflect.Method.invoke(Method.java:597)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:302)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:170)
[13:15:45.213] at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.confluence.util.LoggingContextInterceptor.intercept(LoggingContextInterceptor.java:48)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:47)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.confluence.pages.actions.PageAwareInterceptor.intercept(PageAwareInterceptor.java:114)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.confluence.spaces.actions.SpaceAwareInterceptor.intercept(SpaceAwareInterceptor.java:67)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.confluence.core.actions.LastModifiedInterceptor.intercept(LastModifiedInterceptor.java:39)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.confluence.core.ConfluenceAutowireInterceptor.intercept(ConfluenceAutowireInterceptor.java:25)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.atlassian.xwork.interceptors.XWorkTransactionInterceptor.intercept(XWorkTransactionInterceptor.java:98)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
[13:15:45.213] at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:115)
[13:15:45.213] at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:229)
[13:15:45.213] at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:199)
[13:15:45.213] at javax.servlet.http.HttpServlet.service(HttpServlet.java:92)
[13:15:45.213] at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:106)
[13:15:45.213] at net.itella.confluence.profile.UpdateProfilePictureFilter.doFilter(UpdateProfilePictureFilter.java:62)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:117)
[13:15:45.213] at com.atlassian.confluence.util.profiling.ProfilingPageFilter.parsePage(ProfilingPageFilter.java:137)
[13:15:45.213] at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:51)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at net.itella.confluence.filters.HackedServletContextThreadLocalFilter.doFilter(HackedServletContextThreadLocalFilter.java:19)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.confluence.util.LoggingContextFilter.doFilter(LoggingContextFilter.java:46)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.confluence.util.UserThreadLocalFilter.doFilter(UserThreadLocalFilter.java:44)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:182)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:159)
[13:15:45.213] at net.itella.confluence.ubilogin.ConfluenceUbiloginLoginFilter.doFilter(ConfluenceUbiloginLoginFilter.java:98)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.confluence.util.ClusterHeaderFilter.doFilter(ClusterHeaderFilter.java:35)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:172)
[13:15:45.213] at com.atlassian.spring.filter.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:29)
[13:15:45.213] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:122)
[13:15:45.213] at com.atlassian.core.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:27)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.confluence.util.RequestCacheThreadLocalFilter.doFilter(RequestCacheThreadLocalFilter.java:25)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.core.filters.gzip.GzipFilter.doFilter(GzipFilter.java:61)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:37)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.ubisecure.ubilogin.uwa.UbiloginFilter.doFilter(UbiloginFilter.java:302)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.213] at com.ubisecure.util.filter.ProxyFilter.doFilter(ProxyFilter.java:185)
[13:15:45.213] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
[13:15:45.218] at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:173)
[13:15:45.218] at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
[13:15:45.218] at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:274)
[13:15:45.218] at com.caucho.server.port.TcpConnection.run(TcpConnection.java:511)
[13:15:45.218] at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:516)
[13:15:45.218] at com.caucho.util.ThreadPool.run(ThreadPool.java:442)
[13:15:45.218] at java.lang.Thread.run(Thread.java:619)