After upgrading from 2.2 to 3.0.2 I am receiving a constant stream, about 3 a minute of the following error.

2009-11-02 14:57:30,025 ERROR [DefaultQuartzScheduler_Worker-2] [org.quartz.core.ErrorLogger] schedulerError Job (DEFAULT.ClusterSafetyJob threw an exception.
org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.RuntimeException: More than one cluster safety number in database.]
at org.quartz.core.JobRunShell.run(JobRunShell.java:214)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520)

• Nested Exception (Underlying Cause) ---------------
  java.lang.RuntimeException: More than one cluster safety number in database.
  at com.atlassian.confluence.cluster.safety.HibernateClusterSafetyDao.getClusterSafetyNumberObject(HibernateClusterSafetyDao.java:40)
  at com.atlassian.confluence.cluster.safety.HibernateClusterSafetyDao.setSafetyNumber(HibernateClusterSafetyDao.java:24)
  at com.atlassian.confluence.cluster.safety.DefaultClusterSafetyManager.verify(DefaultClusterSafetyManager.java:36)
  at sun.reflect.GeneratedMethodAccessor247.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:304)
  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:20)
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
  at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
  at $Proxy68.verify(Unknown Source)
  at com.atlassian.confluence.cluster.safety.ClusterSafetyJob.executeJob(ClusterSafetyJob.java:13)
  at com.atlassian.confluence.setup.quartz.AbstractClusterAwareQuartzJobBean.surroundJobExecutionWithLogging(AbstractClusterAwareQuartzJobBean.java:63)
  at com.atlassian.confluence.setup.quartz.AbstractClusterAwareQuartzJobBean.executeInternal(AbstractClusterAwareQuartzJobBean.java:46)
  at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:86)
  at org.quartz.core.JobRunShell.run(JobRunShell.java:203)
  at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520)

I followed the instructions from a a similar bug report CONF-17136 . This didn't help.

RESOLVED? I dropped one of the two rows out of the CLUSTERSAFETY table. This seems to have resolved the issue for now.