Symptoms

Confluence hangs when trying to upgrade the UPM. The following appears in the atlassian-confluence.log, indicating that UPM is being upgraded, but error or warnings are observed:

2012-05-02 11:01:25,162 INFO [pool-5-thread-1] [atlassian.plugin.manager.DefaultPluginManager] disableDependentPlugins Found dependent enabled plugins for uninstalled plugin 'com.atlassian.upm.atlassian-universal-plugin-manager-plugin': [].  Disabling...
2012-05-02 11:01:25,177 INFO [pool-5-thread-1] [atlassian.plugin.manager.DefaultPluginManager] updatePlugin Updating plugin 'com.atlassian.upm.atlassian-universal-plugin-manager-plugin' to 'com.atlassian.upm.atlassian-universal-plugin-manager-plugin'
2012-05-02 11:01:25,177 INFO [pool-5-thread-1] [atlassian.plugin.manager.DefaultPluginManager] notifyPluginDisabled Disabling com.atlassian.upm.atlassian-universal-plugin-manager-plugin

Cause

Your database is not configured to be READ-COMMITTED. To confirm this, run the following SQL query:

SELECT sd.is_read_committed_snapshot_on
FROM sys.databases AS sd
WHERE sd.[name] = '<database name>';

This should return 1. If it returns anything else, proceed to the resolution.

Resolution

For MS SQL

1. Run the following SQL query:

   ALTER DATABASE <database name>
   SET READ_COMMITTED_SNAPSHOT ON
   WITH ROLLBACK IMMEDIATE;

2. Restart Confluence.
3. Re-attempt the UPM upgrade.

For MySQL

1. Stop Confluence

2. (On 3.5.6 onward) In the top level of your Confluence home directory, find the confluence.cfg.xml file and locate the <properties> section. Add the following parameter:

   <properties>
   ...
       <property name="hibernate.connection.isolation">2</property>
   ...
   <properties>

   As an example of where it should be located in the file:

   	<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
       <property name="hibernate.connection.isolation">2</property>
       <property name="hibernate.connection.password">XXXXXX</property>

3. Once this is complete, please start Confluence and attempt the update again