If you’ve previously worked with SharePoint Server 2007 and have created site templates using the Save as Template option then those templates are of file type STP and are not compatible with SharePoint 2010. In order to upgrade existing STP site templates to SharePoint 2010, you need to convert those templates to WSP format.
Unlike saving sites in SharePoint 2010 in WSP file format, when lists or libraries are saved as templates, they are saved as type STP and stored in the site collection’s List Templates Gallery.
Upgrading an existing STP site template to a WSP file can be achieved by performing an in-place upgrade from SharePoint 2007 to SharePoint 2010, as shown in Figure 8.61. Using this method, a new (clean) ...