Your Search Cannot Be Completed Because This Site Is Not Assigned To An Indexer

I had this very annoying error when trying to search my SharePoint Server 2010 single server development machine through code (using the KeywordQuery and FullTextSqlQuery classes).
The search crawler was running and searching from the SharePoint UI returned the expected results.

What you need to do is to...

• Start the "SharePoint Foundation Search"service.
• then go to the select "Manage Content Database Settings" page and select the server running the SahrePoint foundation search service at the drop down menu

Central Administration -> Application Management -> Manage services on server

Central Administration -> Application Management -> Manage Content Database -> (click on database name)

This was not intuitive to me as I was running SharePoint Server Enterpise. And the "SharePoint Server Search" service was already running. Also it strikes me as odd as you do not have the FullTextSqlQuery in SharePoint foundation - you need to have the Enterprise version.