TL;DR: MyGet will retire Facebook, OpenID and StackExchange login to MyGet on March 9, 2018.
Historically, MyGet has been using the Microsoft Azure Access Control Service (ACS). It allowed our users to easily create a MyGet account from an existing third-party login system, like Microsoft Account, Google Account, GitHub authentication, …
With Microsoft sunsetting the ACS service and having to migrate to a different service, we are re-evaluating which third-party login types we want to provide in the future. Right now, only a handful of our users are actively making use of the Facebook, OpenID and StackExchange authentication providers, which prompted us to retire these three providers. MyGet will retire Facebook, OpenID and StackExchange login to MyGet on March 9, 2018.
Affected users have been notified about this via e-mail.
If you are making use of Facebook, OpenID or StackExchange to login to MyGet, it’s always possible to use another third-party identity provider, like Google Account or GitHub. You can link these via your MyGet user profile.
Of course, you can always keep using your MyGet username/password combination to login to MyGet.