authentication - Error "Membership.Provider" property must be an instance of "ExtendedMembershipProvider" - Stack Overflow

Upgrading an existing MVC4 web application to SimpleMembershipProvider and I was getting this error:

"Error “Membership.Provider” property must be an instance of “ExtendedMembershipProvider”"

scratching my head for an hour or so finally found that the two "Bloody" dlls "Webmatrix.data" and "Webmatrix.webdata" has to be set to "Copy to local true". and this resolved the problem.

But what kind of message is this Microsoft????

authentication - Error "Membership.Provider" property must be an instance of "ExtendedMembershipProvider" - Stack Overflow: "Error “Membership.Provider” property must be an instance of “ExtendedMembershipProvider”"

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