We have configured a new identity provider for Sitecore 9.1 using the documented
federatedAuthentication configuration. The identity provider uses OpenID Connect OWIN middleware to authenticate and authorize
extranet users visiting pages on the website.
Using Sitecore item permissions, I am denying access to items for which visitors need to be authenticated to view.
When visiting a page requiring authorization, Sitecore is redirecting my to:
/sitecore/service/noaccess.aspx?item=%2fauthorize&user=extranet%5cAnonymous&site=website with a HTTP response code of 403.
How can I get the identity provider OWIN middleware to initiate the authentication flow when it sees such a response from Sitecore?