Couldn't backup database data

[Ngoc Triet Thai]

Hi, I need helps, I can not backup my confluence server. This is my server's logs.

2018-02-02 10:15:35,096 ERROR [scheduler_Worker-7] [confluence.importexport.impl.BackupJob] executeJob Error while running the scheduled backup
com.atlassian.confluence.importexport.ImportExportException: Couldn't backup database data.
at com.atlassian.confluence.importexport.impl.AbstractXmlExporter.backupEntities(AbstractXmlExporter.java:239)
at com.atlassian.confluence.importexport.impl.AbstractXmlExporter.backupEverything(AbstractXmlExporter.java:104)
at com.atlassian.confluence.importexport.impl.FileXmlExporter.backupEverything(FileXmlExporter.java:94)
at com.atlassian.confluence.importexport.impl.AbstractXmlExporter.doExport(AbstractXmlExporter.java:97)
at com.atlassian.confluence.importexport.impl.FileXmlExporter.doExport(FileXmlExporter.java:53)
at com.atlassian.confluence.importexport.DefaultImportExportManager.exportAs(DefaultImportExportManager.java:120)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
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 com.sun.proxy.$Proxy92.exportAs(Unknown Source)
at com.atlassian.confluence.importexport.impl.BackupJob.executeJob(BackupJob.java:80)
at com.atlassian.confluence.setup.quartz.AbstractClusterAwareQuartzJobBean.surroundJobExecutionWithLogging(AbstractClusterAwareQuartzJobBean.java:64)
at com.atlassian.confluence.setup.quartz.AbstractClusterAwareQuartzJobBean.executeInternal(AbstractClusterAwareQuartzJobBean.java:46)
at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:86)
at org.quartz.core.JobRunShell.run(JobRunShell.java:199)
at com.atlassian.confluence.schedule.quartz.ConfluenceQuartzThreadPool$1.run(ConfluenceQuartzThreadPool.java:20)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:549)
Caused by: java.lang.NullPointerException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.sf.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:96)
at net.sf.hibernate.persister.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:314)
at com.atlassian.confluence.core.persistence.hibernate.HibernateAnyTypeDao$AllPersistentObjectsHandlesLoader.doInHibernate(HibernateAnyTypeDao.java:375)
at com.atlassian.confluence.core.persistence.hibernate.HibernateAnyTypeDao$5.doInHibernate(HibernateAnyTypeDao.java:137)
at org.springframework.orm.hibernate.HibernateTemplate.execute(HibernateTemplate.java:370)
at org.springframework.orm.hibernate.HibernateTemplate.execute(HibernateTemplate.java:337)
at com.atlassian.confluence.core.persistence.hibernate.HibernateAnyTypeDao.findAllPersistentObjectsHandlesUntyped(HibernateAnyTypeDao.java:133)
at com.atlassian.confluence.core.persistence.hibernate.HibernateAnyTypeDao.findAllPersistentObjectsHibernateHandles(HibernateAnyTypeDao.java:127)
at com.atlassian.confluence.importexport.impl.BackupExporter.getHandlesOfObjectsForExport(BackupExporter.java:23)
at com.atlassian.confluence.importexport.impl.AbstractXmlExporter.backupEntities(AbstractXmlExporter.java:218)

[Nic Brough -Adaptavist-]

Usually, this level of log is enough to give us a pointer, so it's a good question.  But in this case, I would want to look further through the log, there should be more error lines that can help us!