Using the following command on Windows Server 2008-R2 works:

Get-Hotfix -cn HOSTNAME | sort InstalledOn -des  | select HotfixID, Description, InstalledOn -first 20

But does not work on Windows Server 2003 (not surprising) OR Server 2008 32-bit (this is what's odd to me).

I get the following error when I run this script on a 32-bit Win 2008 server:

Sort-Object : Exception setting "InstalledOn": "Exception calling "Parse" with "1" argument(s): "String was not recognized as a valid DateTime.""

2 Answers 2


It's throwing the error because it's failing to sort them by Date/Time due to a hotfix with a InstalledOn entry that can't be parsed into a valid Date/Time.

So, most likely you have HotFixes installed on the one machine that don't have a proper "Installed On Date", and so it just returns blank for those entries.

This is not specific to a version of Windows, as I tested this on a Windows 2012 R2 server, and saw the same error.

You can confirm the InstalledOn dates by running the query without the sort:

Get-Hotfix -cn HOSTNAME | select HotfixID, Description, InstalledOn -first 20


PS C:\Windows\system32> Get-Hotfix | select HotfixID, Description, InstalledOn -first 20

HotfixID                                Description                             InstalledOn
--------                                -----------                             -----------
KB2868626                               Security Update
KB2883200                               Update
KB2887595                               Update
KB2894852                               Security Update                         01Dec2015 12:00:00 AM
KB2896496                               Update
KB2900986                               Security Update
KB2903939                               Update
KB2904440                               Update
KB2911106                               Update
KB2919355                               Update                                  04Oct2014 12:00:00 AM

Note above that many of them show nothing for InstalledOn.

  • Not the answer I wanted to hear, but did answer my question. Interestingly, this works locally on the 2008 server, just not remotely from a 2008 R2 server. Oct 22, 2015 at 20:09

Definitly not the best solution, but works for me:

$lastHotFixInstallDate = Get-HotFix | Select-Object @{ 
    'L' = 'installDate';
    'E' = {
        "{0}-{1:00}-{2:00}" -f `
            [Int]$_.PSBase.Properties["installedon"].value.Split('/')[2], `
            [Int]$_.PSBase.Properties["installedon"].value.Split('/')[0], `
}  | Sort-Object -Property installDate | Select-Object -Last 1

This solution utilize the $_.PSBase.Properties["installedon"].value property. Since this property is a string in format m/d/yyyy, it needs to be split manually on the / and sort it afterwards.

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