So I just realized that you require whitelisted callback URLs because I was told by a user of our application that the Login with Twitter was broken. Ran into the same issue. Unreal that it has been this way for so long. It is saying " Error: Please make sure you have at least 2 callback URLs."
I only have one callback URL.
Anyway, in order to move past this issue, I added another URL even though it doesn’t exist, and I have the correct one in place as the first one in my callback URL list on the page. Saved the settings. Tried to login with Twitter into my application. Still doesn’t work.
This is a major breaking change for us. We have been an application that allows sign-ins with Twitter for years, but since you made the breaking change none of our users can login with Twitter anymore.
Also, it’s not clear what you mean by “whitelist”. Where is this? The Settings page doesn’t seem to have a whitelist section?
Please please please advise.