[qubes-users] Trouble updating dom0

Hello. I just did a fresh install of Qubes R4.0.4, and it fails to update dom0 when I do it through the Qubes Updater. Here's the error message:

Updating dom0

Error on updating dom0: Command '['sudo', 'qubesctl', '--dom0-only', '--no-color', 'pkg.upgrade', 'refresh=True']' returned non-zero exit status 1
[ERROR ] Command '['systemd-run', '--scope', 'qubes-dom0-update', '--quiet', '-y', '--clean', '--action=upgrade']' failed with return code: 1
[ERROR ] stderr: Running scope as unit: run-r1316d3efb0a745058090563dc106a7b8.scope
Using sys-firewall as UpdateVM to download updates for Dom0; this may take some time...
*** ERROR while receiving updates:
Domain sys-firewall sent not signed rpm: qubes-mgmt-salt-4.0.25-1.fc25.noarch.rpm
--> if you want to use packages that were downloaded correctly, use dnf directly now
[ERROR ] retcode: 1
Error running 'pkg.upgrade': Problem encountered upgrading packages. Additional info follows: