Non-zero exit status - printf SSH_AUTH_SOCK

When I use vagrantcli up I get following error:

The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!

echo; printf $SSH_AUTH_SOCK

Stdout from the command:

Stderr from the command:

printf: usage: printf [-v var] format [arguments]

Do you know something about that? I have tried different approaches but I couldn’t solve it yet