Cron Authentication Error
Check if you have a module that uses any of the Google's API (translate, maps, youtube, calendar,...). 

Seems that one of the modules implements hook_cron() where is trying to access to one of the Google services through its API.

If that is the case at Google Cloud Platform you can configure a key to solve the issue.

If that is not the problem, try to check the logs to see if you can get more info about this error.