Problem

Plugins are not available after restoring from an XML or Zip site backup or after a recent restart.

Cause

1) This is a result of upgrading using the XML backup rather than the standard upgrade documentation or Production Backup Strategy. Plugins are not saved in the XML backup. See CONFSERVER-6856. If restoring to an existing Confluence instance, all previously installed plugins appear to remain installed after the restore, as they have already been loaded into the classloader and saved onto disk. However, after a restart, these will disappear as the disk is cleared and the plugins are loaded from the database.

2) If only some add-ons are missing and there are no logs tracing they was deleted, this is likely caused by a corrupted plugin cache.

Resolution

1) Restore the plugins manually (from the plugin repository), or use the standard upgrade procedure. If restoring to an already functioning confluence site, immediately restart after restoring and reinstall the plugins.

2) Clear the plugin cache:

1. Shutdown Confluence
2. Ensure the user running Confluence has full read/write privileges to the confluence-home directory.
3. Remove the following directories
    This will remove the plugin cache files only and will not permanently remove any plugins. These directories will be recreated during the next Confluence startup.  However, some third-party plugins may store metadata in these directories, so we recommend creating a temporary backup of the directories.
   
   • <confluence-home>/bundled-plugins
   • <confluence-home>/plugins-cache
   • <confluence-home>/plugins-osgi-cache
   • <confluence-home>/plugins-temp
   • <confluence-home>/bundled-plugins_language
4. Start Confluence