Membership.ValidateUser always returns false after upgrade to VS 2010 / .NET 4.0

Question

Not sure whether this pertains to VS 2010 or to the upgraded framework, but... we are using the Oracle membership provider to authenticate users. Prior to the upgrade everything worked fine, but now Membership.ValidateUser(user, password) returns false despite valid credentials. There is no exception thrown, so it's hard to determine what the problem might be. The website administration tool in VS 2010 is still able to manage users and roles (more or less), so I have no reason to question connectivity. What might the problem be?

Answer 1

The answer (according to this post) is to specify hashAlgorithmType="SHA1" in the Web.config:

<membership defaultProvider="OracleMembershipProvider" hashAlgorithmType="SHA1"/>

This did not solve the problem for existing users, but newly created users can log in now.