Can't remove a space

java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:448)
at java.util.AbstractList$Itr.next(AbstractList.java:419)
at net.sf.hibernate.collection.PersistentCollection$IteratorProxy.next(PersistentCollection.java:441)
at com.atlassian.confluence.spaces.DefaultSpaceManager.removeSpace(DefaultSpaceManager.java:62)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:59)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:201)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
at com.atlassian.confluence.util.profiling.SpringProfilingInterceptor.invoke(SpringProfilingInterceptor.java:17)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:196)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:135)
at $Proxy15.removeSpace(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:59)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:201)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:154)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:196)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:135)
at $Proxy16.removeSpace(Unknown Source)
at com.atlassian.confluence.spaces.actions.RemoveSpaceAction.doRemove(RemoveSpaceAction.java:21)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.opensymphony.xwork.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:308)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:173)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.intercept(DefaultWorkflowInterceptor.java:58)
at com.atlassian.confluence.core.ConfluenceWorkflowInterceptor.intercept(ConfluenceWorkflowInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.atlassian.confluence.core.ConfluenceValidationInterceptor.intercept(ConfluenceValidationInterceptor.java:18)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:40)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:116)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:182)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:162)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:103)
at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:129)
at com.atlassian.confluence.util.profiling.ProfilingPageFilter.parsePage(ProfilingPageFilter.java:36)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:61)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:161)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:181)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:100)
at com.atlassian.confluence.setup.SpringSessionInViewFilter.doFilterInternal(SpringSessionInViewFilter.java:32)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:57)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:38)
at com.caucho.server.http.FilterChainFilter.doFilter(FilterChainFilter.java:88)
at com.caucho.server.http.Invocation.service(Invocation.java:315)
at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:246)
at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:163)
at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
at java.lang.Thread.run(Thread.java:534)