问题
New users cannot log in via Facebook, receiving an error message saying: "Application not available: the application you are trying to use is no longer available or access is limited.".
Users have no problems accessing with their existing Facebook accounts.
回答1:
I get this issue when I create fake/test accounts on facebook. It seems like they take 1-2 hours to review the account before they will let you use the graphAPI.
来源：https://stackoverflow.com/questions/58171374/new-facebook-sdk-application-unavailable-the-applicatioh-you-are-trying-to-use