With the recent up gradation of the Apple developer accounts, I am facing a difficulty that while trying to create the push notification certificates, it is providing me wit
Apple have recently made new changes in APNs and now apple insist us to use "Token Based Authentication" instead of the traditional ways which we are using for push notification.
So does not need to worry about their expiration and this p8 certificates are for both development and production so again no need to generate 2 separate certificate for each mode.
To generate p8 just go to your developer account and select this option "Apple Push Notification Authentication Key (Sandbox & Production)"
Then will generate directly p8 file.
I hope this will solve your issue.
Read this new APNs changes from apple: https://developer.apple.com/videos/play/wwdc2016/724/
Also you can read this: https://developer.apple.com/library/prerelease/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/APNsProviderAPI.html