How to fix Failed to fetch default token error?

Question

I am getting this error after installing in iphone.

Answer 1

Using Xcode8, the fix was to simply enable Keychain Sharing in Capabilities

Open the app.xcworkspace file, select Target > Capabilities > Enable 'Keychain sharing'

Answer 2

Possible reasons for this issue:

1. Device date was not set to the current date.
2. Bundle ID is not same that one you set in GoogleService-Info.
3. .p12 certificate uploaded on Firebase Console is not correct.