Unable to delete space

java.lang.NullPointerException
	at com.atlassian.confluence.core.DefaultContentPropertyManager.cacheGet(DefaultContentPropertyManager.java:168)
	at com.atlassian.confluence.core.DefaultContentPropertyManager.getTextProperty(DefaultContentPropertyManager.java:99)
	at sun.reflect.GeneratedMethodAccessor460.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at com.atlassian.spring.interceptors.SpringProfilingInterceptor.invoke(SpringProfilingInterceptor.java:16)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at $Proxy37.getTextProperty(Unknown Source)
	at sun.reflect.GeneratedMethodAccessor460.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at com.atlassian.plugin.osgi.hostcomponents.impl.DefaultComponentRegistrar$ContextClassLoaderSettingInvocationHandler.invoke(DefaultComponentRegistrar.java:129)
	at $Proxy129.getTextProperty(Unknown Source)
	at sun.reflect.GeneratedMethodAccessor460.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at com.atlassian.plugin.osgi.bridge.external.HostComponentFactoryBean$DynamicServiceInvocationHandler.invoke(HostComponentFactoryBean.java:154)
	at $Proxy129.getTextProperty(Unknown Source)
	at com.adaptavist.confluence.descendentNotification.UserNotificationPreferenceManager.getStringSetFromContentProperties(UserNotificationPreferenceManager.java:223)
	at com.adaptavist.confluence.descendentNotification.UserNotificationPreferenceManager.getSpaceNewsUserWatches(UserNotificationPreferenceManager.java:207)
	at com.adaptavist.confluence.descendentNotification.UserNotificationPreferenceManager.getUsersWatchingNews(UserNotificationPreferenceManager.java:155)
	at com.adaptavist.confluence.descendentNotification.listeners.SpaceEventListener.handleEvent(SpaceEventListener.java:21)
	at com.atlassian.event.legacy.LegacyListenerHandler$LegacyListenerInvoker.invoke(LegacyListenerHandler.java:55)
	at com.atlassian.event.internal.AsynchronousAbleEventDispatcher$2.run(AsynchronousAbleEventDispatcher.java:60)
	at com.atlassian.event.internal.AsynchronousAbleEventDispatcher$1.execute(AsynchronousAbleEventDispatcher.java:28)
	at com.atlassian.event.internal.AsynchronousAbleEventDispatcher.dispatch(AsynchronousAbleEventDispatcher.java:56)
	at com.atlassian.event.internal.EventPublisherImpl.invokeListeners(EventPublisherImpl.java:151)
	at com.atlassian.event.internal.EventPublisherImpl.publish(EventPublisherImpl.java:70)
	at com.atlassian.event.legacy.LegacyEventManager.publishEvent(LegacyEventManager.java:36)
	at com.atlassian.confluence.event.ConfluenceEventManager.publishEvent(ConfluenceEventManager.java:47)
	at sun.reflect.GeneratedMethodAccessor214.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at $Proxy11.publishEvent(Unknown Source)
	at com.atlassian.confluence.spaces.DefaultSpaceManager.removeSpace(DefaultSpaceManager.java:181)
	at com.atlassian.confluence.spaces.DefaultSpaceManager.removeSpace(DefaultSpaceManager.java:129)
	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:597)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at com.atlassian.spring.interceptors.SpringProfilingInterceptor.invoke(SpringProfilingInterceptor.java:16)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at $Proxy43.removeSpace(Unknown Source)
	at com.atlassian.confluence.spaces.actions.RemoveSpaceAction$SpaceRemovalLongRunningTask.runInternal(RemoveSpaceAction.java:95)
	at com.atlassian.confluence.util.longrunning.ConfluenceAbstractLongRunningTask.run(ConfluenceAbstractLongRunningTask.java:21)
	at com.atlassian.confluence.util.longrunning.ManagedTask.run(ManagedTask.java:35)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:662)