Error migrating from Confluence 6.6.0 to 6.6.12

[AntonioM]

Hello.

We are migrating from Confluence 6.6.0 to 6.6.12 When booting version 6.6.12 we are getting this error.

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Populating setup configuration if running with Cluster mode...
ERROR: Unable to start system bundle. (java.lang.IllegalArgumentException: repeated interface: com.atlassian.cluster.monitoring.spi.ClusterMonitoring)
java.lang.IllegalArgumentException: repeated interface: com.atlassian.cluster.monitoring.spi.ClusterMonitoring
at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:597)
at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:557)
at java.lang.reflect.WeakCache$Factory.get(WeakCache.java:230)
at java.lang.reflect.WeakCache.get(WeakCache.java:127)
at java.lang.reflect.Proxy.getProxyClass0(Proxy.java:419)
at java.lang.reflect.Proxy.newProxyInstance(Proxy.java:719)
at com.atlassian.plugin.osgi.hostcomponents.impl.DefaultComponentRegistrar$1.apply(DefaultComponentRegistrar.java:105)
at com.atlassian.plugin.osgi.hostcomponents.impl.DefaultComponentRegistrar.createContextClassLoaderSettingProxy(DefaultComponentRegistrar.java:111)
at com.atlassian.plugin.osgi.hostcomponents.impl.DefaultComponentRegistrar.writeRegistry(DefaultComponentRegistrar.java:75)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager$BundleRegistration$2.run(FelixOsgiContainerManager.java:742)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at com.atlassian.plugin.util.ContextClassLoaderSwitchingUtil.runInContext(ContextClassLoaderSwitchingUtil.java:48)
at com.atlassian.plugin.util.ContextClassLoaderSwitchingUtil.runInContext(ContextClassLoaderSwitchingUtil.java:25)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager$BundleRegistration.loadHostComponents(FelixOsgiContainerManager.java:740)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager$BundleRegistration.start(FelixOsgiContainerManager.java:606)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:645)
at org.apache.felix.framework.Felix$SystemBundleActivator.start(Felix.java:4634)
at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:645)
at org.apache.felix.framework.Felix.init(Felix.java:783)
at org.apache.felix.framework.Felix.start(Felix.java:893)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager$4.run(FelixOsgiContainerManager.java:339)
at java.lang.Thread.run(Thread.java:748)
Exception in thread "Felix:Startup" java.lang.RuntimeException: Unable to start system bundle.
at org.apache.felix.framework.Felix.init(Felix.java:790)
at org.apache.felix.framework.Felix.start(Felix.java:893)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager$4.run(FelixOsgiContainerManager.java:339)
at java.lang.Thread.run(Thread.java:748)

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How can we solve it?
Thanks.

[Brant Schroeder · Accepted solution]

Looks like a plugin issue.  Sometimes this occurs due to bad plugin cache so I would start there and clear it.  https://confluence.atlassian.com/confkb/how-to-clear-confluence-plugins-cache-297664846.html

[AntonioM]

  Hello, indeed that was the problem.

There was some plugin cached.

Thank you very much for your help.