Summary of The Bug

Confluence 4.2.4 installed with 2.7.2 resulting to the following ERROR:

This version of Confluence is unknown to the plugin information server. It may be too new to appear, or it may be some type of non-standard build. No plugins can be found for unknown product versions.

Due the above error, Confluence was not able to search or check for new plugins.

Workaround

1. Access the following URL http://<server base url>/admin/viewplugins.action
2. Uninstall Universal Plugin Manager
3. Shutdown Confluence
4. Remove the following directories
   • <confluence-home>/bundled-plugins
   • <confluence-home>/plugins-cache
   • <confluence-home>/plugins-osgi-cache
   • <confluence-home>/plugins-temp
5. Restart Confluence