What are those “Per User” MSI warning messages about?
If you ever created an update that uses MSI rules you are bound to see a warning message letting you know that the scan agent cannot detect an MSI if it was installed per-user and that you should use different rules to help detect if the update is applicable or installed. There is another similar warning when you select a MSI update that allows per-user installation when inside the Create Update Wizard.
So what are these warnings about? The purpose of the warnings is to inform you that we do not support detection of per-user installed MSI updates using MSI rules. The reason behind this is that if you have installed a MSI under the “User A” account and then scan for the update it will not be detected by the scan engine (running under a different account) and thus cannot be patched. The scan engine runs under the local system account and therefore can only detect MSI’s that are installed system wide.
So what should you do if you must deploy an update for a per-user installed MSI? Don’t rely solely on MSI based rules to detect if your update is applicable or installed. You should use file or registry rules since these will not be user based.
If you don’t know if your update is per-user enabled or not we can help you find out. During the creation of the update in the Create Update Wizard’s “Select Package” page when you browse to your MSI/MSP we will check to see if it has per-user installation enabled. If we detect that it is enable we will display the warning message described above.
