why failed to load?

i cannot enable Cloud Messaging API library for firebase

There was an error while loading /apis/library/googlecloudmessaging.googleapis.com?authuser=0&project=smartguardess-d7952&hl=en. Please try again.
It may be a browser or network issue. Go to the loading issues help page to troubleshoot the issue.
Request ID: 12967462671007524773

i did tried so many ways but nothing works