SFTP connection with ssh key is not possible.

[kpinarci]

I'm unable to connect autorestic using the combination of SFTP and SSH private key.
I'm receiving the following error message: Initializing backend "sftp"...
Error: exit status 1
I'm using the following version: autorestic version 1.7.7

However, when I use the backend like this, it works, but I always have to authenticate with a password:

backends:
  sftp:
    type: sftp
    path: [[email protected]](mailto:[email protected]):/autorestic
    #path: my-storagebox.de:/autorestic
    key: xxxxxxx

my .autorestic.yml

version: 2

locations:
  home:
    from: /opt/data/
    to: sftp

backends:
  sftp:
    type: sftp
    path: my-storagebox.de:/autorestic
    key: xxxx

~/.ssh/config

Host my-storagebox.de
  HostName xxxxx.your-storagebox.de
  Port xxx
  User xxxx
  IdentityFile /home/restic/.ssh/id_ed25519_restic