After upgrading to a new ITMS version, some devices are unable to run inventory tasks. It throws an "unknown" exception.
ITMS 8.x
The Altiris Inventory Agent was not installed.
Ensure that the Inventory Solution plug-in installation policy is enabled and you can find this in the SMP Console in the following locations:
Settings > Agents/Plug-ins > Discovery and Inventory > Windows/UNIX/Linux/Mac > Inventory Plug-in Install
Settings > Console > Views > All Solution Agents Configuration and Rollout > Agents/Plug-ins > Discovery and Inventory > Windows/UNIX/Linux/Mac > Inventory Plug-in Install
NOTE: In some cases it may be enabled but not running on (or targeted to) all clients. Often this is corrected by changing the installation schedule on the installation policy from Run Once ASAP by schedule. The recommendation is to create a schedule time, with no edits (midnight, no repeat) which acts like an ASAP to install immediately once the targeted endpoints receive the policy. Add a scheduled window as a backup up, set to check once per hour and to repeat daily. As long as the target is either the default or includes the dynamic filters used in the default as a starting point of the target, the clients will fall out of the target after installing the Inventory Agent.