ADO. NET provider with invariant name & #39; System. Data. SqlClient & #39; cocould not be loaded,

ADO. NET provider with invariant name 'System. Data. sqlclient' could not be loaded,
The Entity Framework provider type 'System. data. entity. sqlServer. sqlProviderServices, EntityFramework. sqlServer 'registered in the application config file for the ADO. NET provider with invariant name 'System. data. sqlClient 'could not be loaded. make sure that the assembly-qualified name is used and that the assembly is available to the running application. see http://go.microsoft.com/fwlink? LinkId = 260882 for more information.

 

Cause: dll reference is missing. When you reference the EF class library, if you only reference EntityFramework and do not reference EntityFramework. SQL Server will encounter such an error, so the solution to this problem is: addEntityFramework. SqlServer. dll.