Adding Google GCM Api Key Azure Notification Hub Error

Question

We are trying to add our GCM API key to the azure notification hub and we are receiving the following error:

SubCode=40000. Failed to validate credentials with GCM.

Answer 1

Some users may not have verified or registered domain.

With the help of webmaster Tools u can verify and register your domain.

Go to Google Dev Console -> your project ->API's and Auth -> Push -> Click on Learn more for webmaster