I have a site-collection on SharePoint 2013 which is using the SharePoint 2010 experience version and does include a website which is based on a custom site-definition.
When i try to upgrade this site-collection I get the infamous
Missing Site Templates
The following sites are using templates that are not yet supported after upgrade:
Sites that rely on these templates cannot be upgraded at this time, preventing upgrade of this site collection
even if the custom site-definition is very simple.
Unfortunately, the Upgrade web templates for SharePoint 2013 is not very clear;
is the scenario i described above supported at all - or do i have to re-create the custom site-definition for SharePoint 2013?