Error: could not set permissions on ‘/nix/var/nix/profiles/per-user’ to 755: Operation not permitted

1

Hello.

On Ubuntu 21.04 :

ziomario@Z390-AORUS-PRO:~$ curl -L https://nixos.org/nix/install | sh

error: could not set permissions on ‘/nix/var/nix/profiles/per-user’ to 755: Operation not permitted

how to fix it ?