Cannot use localhost as login url in application setting

[neofufu]

In application setting, when setting up login url, I got following error.

Error!
Payload validation error: 'Object didn't pass validation for format absolute-https-uri-or-empty: https://localhost:9999/oauth' on property initiate_login_uri (Initiate login uri, must be https).

Somewhere in this forum, I saw exact same issue 2 years ago.
For callback and logout url, https://localhost simply works BUT it does not with login url.
Is there specific reasoning for that?

I am trying out our app with my free account so that we can move quickly once our team officially starts migration, and using localhost would be the quickest for us.

[tyf]

Hey there @neofufu welcome to the community!

I did a bit of digging myself and this was never explicitly addressed - You can get around it by adding 127.0.0.1 rather than localhost for testing purposes.