token is null

I use this library and when try to get token i see this error on xcode log:
Failed to fetch default token Error Domain=com.firebase.iid Code=0 "(null)"

i think this problem is because firebasemessaging is filter for my country ,
is anyone can help me what should i do?

i found this topic
Convert APNS Tokens To FCM Tokens With Simple HTTP APIs
but when use regstiration-token for sending message the response is invalid-registration

this problem is just on ios