ERROR : The provider did not return a ProviderManifest instance. Could not determine storage version; a valid storage connection or a version hint is required. ../path/SampleDB.edmx Project Name - usinessObject

While using Entity framework, for the above error you had to open your .edmx file with Notepad and edit <Scheme> tag inside <edmx:StorageModels>.
You need to edit ProviderManifestToken="2012" to ProviderManifestToken="2008"

Happy Coding !!!