This was a tough error, THAT IS AN UPGRADE SHOWSTOPPER, that I ran into a few months ago. Just now getting around to blogging it. Here's the full error: [powershell] [SPSiteWssSequence] [ERROR] [9/29/2011 12:02:27 PM]: Action 4.0.23.0 of Microsoft.SharePoint.Upgrade.SPSiteWssSequence
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