When configuring a Search Result Source in Central Administration, if you come across an error like this in the subject line, it’s very simple to fix.

You justneed to activate the “Search Server Web Parts and Templates” feature.

Just go to SharePoint Management Shell (run as administrator) and run this command:
Enable-SPFeature SearchWebParts -url http://<Your Central Admin Url>

Refresh the Search Results Page and you’re good to go.