I am trying to deploy a go 1.11 runtime that used to work, but recently I\'ve been getting: ERROR: (gcloud.app.deploy) INVALID_ARGUMENT: unable to resolve sou
Try disabling and enabling the Cloud Build API in your project so a new service account is created, then try to deploy again.
This ensures that Cloud Build has permission to start builds (the service account name should look like project-number@cloudbuild.gserviceaccount.com).