metasploit – Meterpreter download will not work

I'm trying to follow a step-by-step procedure for a CTF and there is a point where I have to download a unix-privesc-check file on the other machine. Fine when i use the command i get this answer

upload / root / unix-privesc-check
[*] loading: /root/unix-privesc-check/README.md -> unix-privesc-check / README.md
[-] core_channel_open: the operation failed: 1

Someone knows why I am getting this error and how can I get around it.

Thank you!