Symptoms

Bundled plugins, like the Usage Tracking or Mail Page plugin, become disabled mysteriously. Logs contain messages like:

2010-05-17 19:19:13,618 INFO [main] [atlassian.plugin.manager.DefaultPluginManager] updatePlugin Updating plugin 'com.atlassian.confluence.ext.usage:0.12' to 'com.atlassian.confluence.ext.usage:0.13'
2010-05-17 19:19:13,619 INFO [main] [atlassian.plugin.manager.DefaultPluginManager] notifyPluginDisabled Disabling com.atlassian.confluence.ext.usage

Cause

A Confluence administrator has updated the plugin to a version which is listed as compatible, but which proves to be incompatible.

Resolution

1. Uninstall the plugin from the Administration console.

2. Restart Confluence. This will reload the plugin.