When upgrading to Entity Framework remember to put the providerName attribute on your connection string element in the web.config
<add name="FVLBEntities"
connectionString="metadata=res://*/DB.csdl|res://*/DB.ssdl|res://*/DB.msl;provider=System.Data.SqlClient;provider connection string="data source=sqlserver;initial catalog=my_database;integrated security=True;multipleactiveresultsets=True;App=EntityFramework""
providerName="System.Data.EntityClient"/>