Problem

When trying to upgrade the Universal Plugin Manager (UPM), the installation hangs (more than 5 to 10 minutes) as seen here: 

The following appears in the atlassian-confluence.log:

2014-10-23 10:38:32,406 INFO [pool-17-thread-1] [atlassian.plugin.manager.DefaultPluginManager] updatePlugin Updating plugin 'com.atlassian.upm.atlassian-universal-plugin-manager-plugin' from version '2.17.5' to version '2.18'
2014-10-23 10:38:32,408 INFO [pool-17-thread-1] [atlassian.plugin.manager.DefaultPluginManager] notifyPluginDisabled Disabling com.atlassian.upm.atlassian-universal-plugin-manager-plugin
2014-10-23 10:38:33,984 WARN [pool-17-thread-1] [plugins.createcontent.extensions.BlueprintModuleDescriptor] init i18n-name-key is a required attribute of <blueprint> for module: com.gliffy.integration.confluence:gliffy-blueprint
-- referer: https://avwikitestupgrade.xxxxx.com:8443/plugins/servlet/upm | url: /rest/plugins/self-update/1.0/ | userName: xxxx
2014-10-23 10:39:34,100 INFO [pool-17-thread-1] [atlassian.plugin.manager.DefaultPluginManager] notifyPluginDisabled Disabling com.atlassian.confluence.extra.team-calendars
2014-10-23 10:40:37,887 ERROR [http-bio-8443-exec-25] [confluence.status.service.DefaultSystemInformationService] getModifications
-- referer: https://avwikitestupgrade.xxxxx.com:8443/plugins/servlet/stp/view/ | url: /plugins/servlet/stp/view/detect-issues/view | userName: xxxx

Diagnosis

Disable all plugins manually (do not enable safe mode) and try to update the UPM.

Cause

There is a plugin that is causing conflict that, in turn, causes the install to hang.  

Workaround

Disable all plugins and run the UPM.  

Resolution

To find the offending plugin, please use the following steps after you have confirmed the update works when disabling plugins.

1. Stop the Confluence service

2. Run this query on your database:

     select plugindataid,pluginkey,filename,lastmoddate from plugindata;

3. Please make note of what plugindataid is associated with the com.atlassian.upm.atlassian-universal-plugin-manager-plugin

4. Then run:

   delete from plugindata where plugindataid = <pluginid from upm>;

   changing <pluginid from upm> to the number you found in step 3

5. Delete the following folders
   • <confluence-home>/bundled-plugins
   • <confluence-home>/plugins-cache
   • <confluence-home>/plugins-osgi-cache
   • <confluence-home>/plugins-temp
   • <confluence-home>/bundled-plugins_language

6. With all of the plugins disabled, re-enable each plugin one-at-a-time and try to update the UPM

7. Once the offending plugin is found, either remove or update the plugin