error: the required argument <snap>:<slot> was not provided.

[abdullahc]

After installing ufw using snap. Snap fails to connect interfaces, raising the following error message:

$ ufw
Could not use iptables. Please run:
  'sudo snap connect ufw:firewall-control ubuntu-core:firewall-control'

$ sudo snap connect ufw:firewall-control ubuntu-core:firewall-control
error: the required argument <snap>:<slot> was not provided.

However, I found a trick that make snap accept it. Documented in https://askubuntu.com/questions/787529/16-04-lts-ufw-version

1. Run

    sudo snap connect snappy-debug:log-observe ubuntu-core:log-observe

    You get an error ignore it.

1. Then again run

    sudo snap connect ufw:firewall-control ubuntu-core:firewall-control

Now, it does work without problem.

$ snap interfaces
Slot Plug
:cups-control -
:firewall-control ufw
...

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: snap (not installed)
ProcVersionSignature: Ubuntu 4.4.0-24.43-generic 4.4.10
Uname: Linux 4.4.0-24-generic x86_64
NonfreeKernelModules: i915
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Tue Jun 21 03:31:53 2016
InstallationDate: Installed on 2015-05-11 (406 days ago)
InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: snap
UpgradeStatus: No upgrade log present (probably fresh install)

[Paweł Stołowski (stolowski)]

I cannot reproduce the original problem with establishing firewall-control interface (works fine with snapd 2.13), please re-check and comment if it's still happening with up-to-date system.
I have however hit another problem related to this interface and opened a new bug #1618737.

[Launchpad Janitor (janitor)]

[Expired for snapd (Ubuntu) because there has been no activity for 60 days.]