Man, why do i always have to learn the stuff the hard way?
I was doing a deployment of my RIA solution to the production server after a visual studio update (not sure if it’s connected or not), and i would start getting these strange errors when trying to log in:

There was a failure using the default ‘ProfileProvider’. Please make sure it is configured correctly. The database ‘C:INETPUBWWWROOTAPP_DATAASPNETDB.MDF’ cannot be opened because it is version 661. This server supports version 655 and earlier. A downgrade path is not supported.
Cannot open user default database. Login failed.
Login failed for user ‘NT AUTHORITYNETWORK SERVICE’. InnerException message: The database ‘C:INETPUBWWWROOTAPP_DATAASPNETDB.MDF’ cannot be opened because it is version 661. This server supports version 655 and earlier. A downgrade path is not supported.
Cannot open user default database. Login failed.
Login failed for user ‘NT AUTHORITYNETWORK SERVICE’.

The trouble is, i wasn’t using aspnedb.mdf at all. I figured i would just delete the database and everything would be fine. Then i got this:

Load operation failed for query ‘Login’. Access to the path ‘C:inetpubwwwrootApp_data’ is denied.

Seems that asp.net membership provider is trying to create that ASPNETDB.MDF file on the server although i’ve set it up (or so i thought) to use my database.

My web.config part (the one that’s important) looks like this:

    <profile>
      <providers>
        <add name="CustomizedProfileProvider" type="System.Web.Profile.SqlProfileProvider"
             connectionStringName="database"
             applicationName="/AltiFin"/>
      </providers>
      <properties>
        <add name="FriendlyName"/>
        <add name="BranchGuid" type="System.Nullable`1[System.Guid]"/>
      </properties>
    </profile> 

To cut the long story short, you should ALWAYS set defaultProvider on all the asp.net providers like this:

    <profile defaultProvider="CustomizedProfileProvider"> <!--This part on the left! -->
      <providers>
        <clear/> <!--you should also put this on the left -->
        <add name="CustomizedProfileProvider" type="System.Web.Profile.SqlProfileProvider"
             connectionStringName="database"
             applicationName="/AltiFin"/>
      </providers>
      <properties>
        <add name="FriendlyName"/>
        <add name="BranchGuid" type="System.Nullable`1[System.Guid]"/>
      </properties>
    </profile> 

Otherwise asp.net membership will try to create a default database. just to be safe, you should also put the tag before add, so it doesn’t create the mdf file without you knowing it (like it did on my dev machine). Hope this helps!