Custom Saml2SecurityTokenHandler - The token Serializer cannot serialize

For the sake of simplicity, I've implemented the following class:

public class CustomUserNamePasswordValidatorSecurityTokenHandler : UserNameSecurityTokenHandler {}

And I've enabled it configuration (and enabled proper configSection):

  <microsoft.identityModel>
    <service>
      <securityTokenHandlers>
        <clear />
        <add type="CustomUserNamePasswordValidatorSecurityTokenHandler" />       
      </securityTokenHandlers>
    </service>
  </microsoft.identityModel>

And performing an actual RP call against my STS yields (in service trace viewer):

The token Serializer cannot serialize 'Microsoft.IdentityModel.Tokens.SessionSecurityToken'. If this is a custom type you must supply a custom serializer.

If I comment out the configuration (so no token handler applys), everything works fine. How do I supply this custom serializer?

NOTE: There's a couple references to the issue in this thread however I don't see the开发者_StackOverflow中文版 resolution.

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Removing the <clear /> on the securityTokenHandler section should suffice (I editied may answer on your other question accordingly, sorry).

<clear /> removes all by default registered handlers (e.g. for the SessionSecurityToken).