Nmcli error - "failed to update connection: error writing to file"

Ask Fedora
1

nmcli command cannot modify NetworkManager connections:

nmcli connection modify <conn> ipv6.ip6-privacy 0
Error: Failed to modify connection '<conn>': failed to update connection: error writing to file '/etc/NetworkManager/system-connections/<conn>.nmconnection': failed to create file /etc/NetworkManager/system-connections/<conn>.nmconnection.ANXVP3: Read-only file system

This happens even after setenforce 0, so cannot be about SElinux.

Obviously, system is writable - I can edit the file myself. I execute the command as root.

This happens with the KDE applet also. Of course the files belong to root and have 600 permissions - but this is mandatory (otherwise NM just rejects the connection whatsoever). But normally, users can do this without root permissions!

Note: I use GNU Stow to manage connections info in a git repo. These connections have been pulled from the repo - but seem to work just fine (also with applet) - until I needed to modify an option. I know I can edit the files directly (that’s what I do currently) - but would be nice to understand what happens there, and also let the graphical configuration with KDE applet work.

Could anyone provide some insights on:

  • why this happens (esp. as root!)
  • how exactly NM handles connection files (esp. when working from the DE without root!)

Thank you!

System infos:

  • Fedora 43

Relevant app infos:

  • NetworkManager-1.54.3-2.fc43
2

That looks odd.

What do you see if you do these commands?

lsblk -f
sudo touch /etc/NetworkManager/system-connections/q.q
3

lsblk -f (relevant portion, UUIDs redacted):

└─nvme0n1p5                                   crypto_LUKS 2            <uuid>                
  └─luks-<uuid> btrfs             fedora <uuid>  357.5G    17% /var
                                                                                                       /tmp
                                                                                                       /usr/local
                                                                                                       /opt
                                                                                                       /home
                                                                                                       /.snapshots
                                                                                                       /

sudo touch /etc/NetworkManager/system-connections/test works fine, as expected:

sudo ls -l /etc/NetworkManager/system-connections/test
-rw-r--r--. 1 root root 0 May 24 16:20 /etc/NetworkManager/system-connections/test

As mentioned, I would not be able to modify the files manually if something was wrong with the FS mounting.

4

The actual file operations are performed by NetworkManager.service, which runs as root. It exposes a D-Bus service which can be called (potentially by non-root users) to create/edit connection files.

5

Do you mean that you used Stow to create files in /etc/NetworkManager/system-connections that are actually symlinks to a git repo?