You would see this if you open a Visio 2010 or earlier file in Visio 2016 or later. The eVSM v11 (and earlier versions) startup template is in Visio 2010 format, so you may see this when starting new maps.
You can ignore this and continue working as normal. To eliminate the message, you can save your map file in the current version of Visio (*.vsdm format) through "File > Save As".