I am trying to enable Cloud Messaging API (Legacy) in firebase console, because I need the server key for building my flutter apps. but when I try try to enable it, by clicking Manage API in Google Cloud Console, the result is:
There was an error while loading /apis/library/googlecloudmessaging.googleapis.com?authuser=1&project=xxxxxx. Please try again.
It may be a browser or network issue. Go to the loading issues help page to troubleshoot the issue.
Is there a way to enable Cloud Messaging API (Legacy)?
The legacy API has been superseded since 2018, deprecated since June 2023, and will be removed in the coming weeks. There's no way to still enable it on new projects. I recommend reading the documentation on migrating from legacy FCM APIs to HTTP v1.