I had apparently left out some ultimately pertinent information when I originally posted. This included the fact that the error was being thrown by the membership services; specifically the ... SimpleMembershipInitializer ... originally this class specified the connection string ... "DefaultConnection" defined in the web.config, to be used when initializing the database connection.
WebSecurity.InitializeDatabaseConnection("DefaultConnection", "Users", "UserId", "UserName", autoCreateTables: false);
I had changed it to use the "DBCatalogContext" connection string I had added to the web.config, thinking that I would use this single connection string instead. The problem, of course, is that the new connection string that I added was an Entity Framework connection string which the membership services did not recognize resulting in the data provider error.
I simply added back the original, regular connection string, in addition to the Entity Framework connection string and now everything works. Well everything relating to this issue ...
<connectionStrings>
<add name="DBCatalogContext"
connectionString="metadata=res://*/DBCatalog.csdl|
res://*/DBCatalog.ssdl|
res://*/DBCatalog.msl;
provider=System.Data.SqlClient;
provider connection string="data source=.\SQLEXPRESS;
initial catalog=DBCatalog;
integrated security=True;
multipleactiveresultsets=True;
App=EntityFramework""
providerName="System.Data.EntityClient" />
<add name="DefaultConnection"
providerName="System.Data.SqlClient"
connectionString="data source=.\SQLEXPRESS;initial catalog=DBCatalog;integrated security=True;multipleactiveresultsets=True;App=EntityFramework" />
</connectionStrings>
I hope that someone else can find this helpful.