Known Issues

MacOS 10.15 "Catalina"

There is an unsolved issue with the root(/) file system in 10.15 being read-only: https://github.com/NixOS/nix/issues/2925

Our current recommended workaround is putting /nix under /opt/nix and symlinking it via /etc/synthetic.conf:

sudo mkdir /opt/nix
sudo chown ${USER} /opt/nix
sudo sh -c "echo 'nix\t/opt/nix' >> /etc/synthetic.conf"
reboot

After the system reboots you should see the /nix symlink in place:

 % ls -l /nix
lrwxr-xr-x  1 root  wheel  8 Oct 11 13:53 /nix -> /opt/nix

In order to be able to use Nix with a symlinked /nix you need to include this in your shell:

export NIX_IGNORE_SYMLINK_STORE=1

Add it to your .bashrc or any other shell config file.

NOTE: Your old /nix directory will end up in /Users/Shared/Relocated Items/Security/nix after OS upgrade.

If copying from Nix Cache times out you can adjust the timeout by changing nix/nix.conf:

stalled-download-timeout = 9001

When building Android on NixOS you might encounter the following error:

ignoring the user-specified setting 'extra-sandbox-paths', because it is a restricted setting and you are not a trusted user

You can mitigate this by setting the nix.trustedUsers property.