Updated Certificate for Game Center Authentication
On November 12, 2018, a new certificate for server-based Game Center Player ID verification will be available via the publicKeyUrl property of generateIdentityVerificationSignature, and the previous certificate will expire.
Read Also 64-bit Requirement for Mac Apps
Make sure your app always retrieves and uses the current publicKeyUrl value so it automatically uses the new certificate. If your app caches the certificate or hardcodes the certificate URL, it will require an update.