I got the following error when I used sqlce 4.0 with entityframework 6.0
No Entity Framework provider found for the ADO.NET provider with invariant name \'Sy
ErikEJ has pointed this out, but I'd like to highlight the fact, you MUST remember to install the Nuget package
EntityFramework.SqlServerCompact
I tried following the recommended answer, but didn't realise I didn't have the required NuGet package the App.config was referencing.