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I had the same problem. Avast is not able to use/connect with GCM (Google Cloud Messaging). Try logging into your Gmail account on the device and make sure it’s working. Sounds strange, I know. But it has worked for many people. Also try deleting your google account from the device (Settings → Accounts) and re-add it. There are other solutions you can find by searching Google for “PHONE_REGISTRATION_ERROR gcm”.