• Variant XXX has failed: Error sending payload to GCM server: HTTP Status Code: 301(): the 301 error (Moved Permanently) happens because GCM is not supported anymore by google as May 2019
• Variant XXX has failed: Error sending payload to APNs server: javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_expired happens because the certificate inside the P12 file attached to the iOS variant has expired. To resolve it, just replace the P12 file with a new one using the server Admin UI.

We are still in the process of writing migration documentations. See AEROGEAR-10131