When trying to connect to you sftp service and you receive an error like
when using a GCS backend it is likely a permissions issue with your user account on your backend.
The error from GCS that we receive in our logs at this time is:
failed to connect and get bucket information: googleapi: Error 403: username@gcs-ID.iam.gserviceaccount.com does not have storage.buckets.get access to bucketname., forbidden
The resolution is to use the permission level storage legacy bucket owner for the user trying to connect in GCS