After attempting to install or upgrade the Endpoint Encryption Deployment Tool, the installation or upgrade is unsuccessful, and then the Upgrade and Uninstall buttons are disabled in Plug-in Manager.
This issue may occur because of a registry issue.
Export the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\TrendMicro\OfficeScan\service\AoS\OSCE_ADDON_TMEE_TOOLBOX.
Contact Trend Micro Support and send the support representative that registry key. Trend Micro Support will help you to resolve this issue.