Sometimes the Gliffy Confluence plugin has trouble starting after a Confluence server restart, or after a plugin upgrade. When this occurs, the Confluence server starts up with the plugin in the "disabled" state. This can be caused by any number of problems.
- Update the Atlassian UPM to the latest version.
- Update the Gliffy plugin to the latest version, if possible.
- Perform a full un-install and re-install of the Gliffy plugin, by following the instructions at this URL: http://support.gliffy.com/entries/25696104
If the problem still persists, please contact Gliffy support.