Backup of other Installation not found in S3 for restore

Hi everyone,

I have 2 installations of GitLab on AWS which store their regularly taken backups in S3.

My task is to do a cross-restore from one backup to the other installation.
So I copied the latest backup of the source installation into the S3 bucket of the target installation´.

I can see it when doing an “aws s3 ls” on the bucket, which tells me that it is in the correct location and the instance profile to access S3 works:

[root@ip-10-77-131-43 ~]# aws s3 ls man-cicd-prod-de-gitlab-backup
2018-08-14 07:39:27      92160 1533951017_2018_08_11_11.1.4-ee_gitlab_backup.tar
2018-08-14 09:24:14  958904320 1534206717_2018_08_14_11.1.4-ee_gitlab_backup.tar
2018-08-14 07:39:47      92160 1534210217_2018_08_14_11.1.4-ee_gitlab_backup.tar

When I issue the restore-command, the backup is not found though:

[root@ip-10-77-131-43 ~]# gitlab-rake gitlab:backup:restore BACKUP=1534206717_2018_08_14_11.1.4-ee
The backup file 1534206717_2018_08_14_11.1.4-ee_gitlab_backup.tar does not exist!

It is also not listed when I just do not specify any backup:

    [root@ip-10-77-131-43 ~]# gitlab-rake gitlab:backup:restore
    Found more than one backup:
     1534210217_2018_08_14_11.1.4-ee
     1533951017_2018_08_11_11.1.4-ee
    Please specify which one you want to restore:
    rake gitlab:backup:restore BACKUP=timestamp_of_backup

I CAN successfully restore the other backups that have been done by the target instance itself, which also tells me that the configuration of backup_upload_connection and backup_upload_remote_directory in /etc/gitlab/gitlab.rb are correct
.
But I thought putting the backup file of the other instance of the exact same version (11.1.4 EE) in that location should work according to the documentation.

What can I do to get my cross-restore done? Is there any “backup file inventory” I would have to add my file to?

Kind regards,
Robert