Finally solved it thanks to information found in this blog post: http://insomniacgeek.com/to-call-this-method-the-membership-provider-property-must-be-an-instance-of-extendedmembershipprovider/ and some googling.
In essence I needed to add this to my app.config file:
<system.web>
<profile defaultProvider="SimpleProfileProvider">
<providers>
<add name="SimpleProfileProvider" type="WebMatrix.WebData.SimpleMembershipProvider, WebMatrix.WebData"
connectionStringName="DefaultConnection" applicationName="/" />
</providers>
</profile>
<membership defaultProvider="SimpleMembershipProvider">
<providers>
<add name="SimpleMembershipProvider" type="WebMatrix.WebData.SimpleMembershipProvider, WebMatrix.WebData" />
</providers>
</membership>
<roleManager defaultProvider="SimpleRoleProvider" enabled="true">
<providers>
<add name="SimpleRoleProvider" type="WebMatrix.WebData.SimpleRoleProvider, WebMatrix.WebData"/>
</providers>
</roleManager>
</system.web>
Please note the enabled="true"
on the roleManager
element. Without that the same exception will be thrown.