Issue with Open ID Authentication after Azure App Service Upgrade

Question

Today, on August 31, 2023, we initiated an upgrade for our Azure App Service from Standard S2 to Premium S2. However, during this upgrade process, we encountered an unexpected issue related to the Open ID Authentication with Azure.

Before the upgrade, our login page featured an image of the Microsoft logo, which directed users to the Microsoft login page upon interaction. Regrettably, this functionality is no longer operational following the upgrade. Upon inspecting the source code of the web page, it's apparent that the entire login section does not load. There is no error.

In our codebase, we employ the following line to gather all external logins:

var loginProviders = Context.GetOwinContext().Authentication.GetExternalAuthenticationTypes();

It appears that this code segment is no longer functioning as expected. We have ensured that no alterations were made to the client ID or secret, which leads us to inquire whether the issue could be related to the recent upgrade to the Premium plan or if any changes have occurred within the Azure Active Directory.

We are reaching out for assistance and guidance in resolving this matter promptly. Any insights, suggestions, or solutions you could provide would be greatly appreciated. Our aim is to reinstate the seamless Open ID Authentication experience for our users.