GCM send calls are failing -Android https://android.googleapis.com/gcm/send (push notification)

[ishwarpatidar75]

Hi GCM Team,

While calling API - https://android.googleapis.com/gcm/send we are getting "http_status_code=401" respond and its failing push notification calls.
Our logs has following exception:
GCM Connector,ERROR_MESSAGE=An exception is caught in GCM communication. java.io.IOException: Could not send message after 2 attempts,STATE=FAILED
We have also verified Authorization: key='' and it has start date from 2016-08-16 05:19

This issue observed post 29th-Aug-2018. Is there any recent changes/update went at GCM/send API.
Kindly let us know.
Regards,
Ishwar

[Harif-Rahman]

check for the url end point presence in Sender class if it is not then it wont send