Missing Open XML SDK 2.5 for Microsoft Office

If you get this error (in this case from Dynamics NAV 2015)…

A call to Microsoft.DynamicsNav.OpenXml.Spreadsheet.WorkbookWriter.Create failed with this message: Could not load file or assembly 'DocumentFormat.OpenXml, Version=2.5.5631.0, Culture=neutral,PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

…it’s probably because Open XML SDK 2.5 for Microsoft Office has not been installed on your computer.

The installer is included with the Dynamics NAV 2015 setup files under Prerequisite Components\Open XML SDK 2.5 for Microsoft Office\.