title: Display custom errors when using ASP.NET MembershipProvider
body: <p>I'm using a custom <code>MembershipProvider</code> in my application, and it's all wired up correctly. The only missing piece is the ability to display custom error messages depending on the result of the authentication.</p>
  
  <p>The <code>ValidateUser()</code> method only returns <code>true</code> or <code>false</code>, but I would like to also return a more detailed message in case the validation fails. At the moment I'm using a <code>Session</code> variable to store it, and then read that variable in the login page.</p>
  
  <p>Is there a better way of doing it?</p>