"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."
OR
"Exception Details: System.InvalidOperationException: 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."
Whilst doing migrations from EF4 to EF6, I came across the following error. This is caused by two different things
1.) Your project contains both EF4 and EF6 references. If you're using EF6, only EF6 can be in the project. Either remove everything EF4 related, or upgrade it to EF6.
2.) You're missing a DLL. This seems to be the most common error. Navigate to applicationPath\bin\ on the server, and look for EntityFramework.SqlServer.dll (Should be around 600KB). For some odd reason, it rarely gets included in deployments. If it's not there, simply copy the version from your development machine onto the server, and you're good to go!
