If you’re getting the following error upgrading TFS 2012 RTM to ver. 2012.3:

TF255356: The following error occurred when configuring the Team Foundation databases:
TF400711: Error occurred while executing servicing step Upgrade Warehouse for component UpdateWarehouseVersion during FinishInstallUpdates: Could not load file or assembly ‘Microsoft.AnalysisServices, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91‘ or one of its dependencies. The system cannot find the file specified.. For more information, see the configuration log.

then just install Microsoft SQL Server 2012 Analysis Management Objects from Microsoft SQL Server 2012 Feature Pack (expand the Install Instructions node).

Note that you’ll might need to restart the setup wizard or even server itself before the error will go away.